diff --git a/Userland/Applications/FileManager/PropertiesWindow.cpp b/Userland/Applications/FileManager/PropertiesWindow.cpp
index 49817731ac8..6264f6f6945 100644
--- a/Userland/Applications/FileManager/PropertiesWindow.cpp
+++ b/Userland/Applications/FileManager/PropertiesWindow.cpp
@@ -246,7 +246,7 @@ ErrorOr<void> PropertiesWindow::create_file_type_specific_tabs(GUI::TabWidget& t
     return {};
 }
 
-ErrorOr<void> PropertiesWindow::create_archive_tab(GUI::TabWidget& tab_widget, NonnullRefPtr<Core::MappedFile> mapped_file)
+ErrorOr<void> PropertiesWindow::create_archive_tab(GUI::TabWidget& tab_widget, NonnullOwnPtr<Core::MappedFile> mapped_file)
 {
     auto maybe_zip = Archive::Zip::try_create(mapped_file->bytes());
     if (!maybe_zip.has_value()) {
@@ -268,7 +268,7 @@ ErrorOr<void> PropertiesWindow::create_archive_tab(GUI::TabWidget& tab_widget, N
     return {};
 }
 
-ErrorOr<void> PropertiesWindow::create_audio_tab(GUI::TabWidget& tab_widget, NonnullRefPtr<Core::MappedFile> mapped_file)
+ErrorOr<void> PropertiesWindow::create_audio_tab(GUI::TabWidget& tab_widget, NonnullOwnPtr<Core::MappedFile> mapped_file)
 {
     auto loader_or_error = Audio::Loader::create(mapped_file->bytes());
     if (loader_or_error.is_error()) {
@@ -317,10 +317,10 @@ struct FontInfo {
     Format format;
     NonnullRefPtr<Gfx::Typeface> typeface;
 };
-static ErrorOr<FontInfo> load_font(StringView path, StringView mime_type, NonnullRefPtr<Core::MappedFile> mapped_file)
+static ErrorOr<FontInfo> load_font(StringView path, StringView mime_type, NonnullOwnPtr<Core::MappedFile> mapped_file)
 {
     if (path.ends_with(".font"sv)) {
-        auto font = TRY(Gfx::BitmapFont::try_load_from_mapped_file(mapped_file));
+        auto font = TRY(Gfx::BitmapFont::try_load_from_mapped_file(move(mapped_file)));
         auto typeface = TRY(try_make_ref_counted<Gfx::Typeface>(font->family(), font->variant()));
         typeface->add_bitmap_font(move(font));
         return FontInfo { FontInfo::Format::BitmapFont, move(typeface) };
@@ -349,9 +349,9 @@ static ErrorOr<FontInfo> load_font(StringView path, StringView mime_type, Nonnul
     return Error::from_string_view("Unrecognized font format."sv);
 }
 
-ErrorOr<void> PropertiesWindow::create_font_tab(GUI::TabWidget& tab_widget, NonnullRefPtr<Core::MappedFile> mapped_file, StringView mime_type)
+ErrorOr<void> PropertiesWindow::create_font_tab(GUI::TabWidget& tab_widget, NonnullOwnPtr<Core::MappedFile> mapped_file, StringView mime_type)
 {
-    auto font_info_or_error = load_font(m_path, mime_type, mapped_file);
+    auto font_info_or_error = load_font(m_path, mime_type, move(mapped_file));
     if (font_info_or_error.is_error()) {
         warnln("Failed to open '{}': {}", m_path, font_info_or_error.release_error());
         return {};
@@ -398,7 +398,7 @@ ErrorOr<void> PropertiesWindow::create_font_tab(GUI::TabWidget& tab_widget, Nonn
     return {};
 }
 
-ErrorOr<void> PropertiesWindow::create_image_tab(GUI::TabWidget& tab_widget, NonnullRefPtr<Core::MappedFile> mapped_file, StringView mime_type)
+ErrorOr<void> PropertiesWindow::create_image_tab(GUI::TabWidget& tab_widget, NonnullOwnPtr<Core::MappedFile> mapped_file, StringView mime_type)
 {
     auto image_decoder = Gfx::ImageDecoder::try_create_for_raw_bytes(mapped_file->bytes(), mime_type);
     if (!image_decoder)
@@ -456,7 +456,7 @@ ErrorOr<void> PropertiesWindow::create_image_tab(GUI::TabWidget& tab_widget, Non
     return {};
 }
 
-ErrorOr<void> PropertiesWindow::create_pdf_tab(GUI::TabWidget& tab_widget, NonnullRefPtr<Core::MappedFile> mapped_file)
+ErrorOr<void> PropertiesWindow::create_pdf_tab(GUI::TabWidget& tab_widget, NonnullOwnPtr<Core::MappedFile> mapped_file)
 {
     auto maybe_document = PDF::Document::create(mapped_file->bytes());
     if (maybe_document.is_error()) {
diff --git a/Userland/Applications/FileManager/PropertiesWindow.h b/Userland/Applications/FileManager/PropertiesWindow.h
index 1e3f3de9969..cbf54466dbf 100644
--- a/Userland/Applications/FileManager/PropertiesWindow.h
+++ b/Userland/Applications/FileManager/PropertiesWindow.h
@@ -30,11 +30,11 @@ private:
     ErrorOr<void> create_widgets(bool disable_rename);
     ErrorOr<void> create_general_tab(GUI::TabWidget&, bool disable_rename);
     ErrorOr<void> create_file_type_specific_tabs(GUI::TabWidget&);
-    ErrorOr<void> create_archive_tab(GUI::TabWidget&, NonnullRefPtr<Core::MappedFile>);
-    ErrorOr<void> create_audio_tab(GUI::TabWidget&, NonnullRefPtr<Core::MappedFile>);
-    ErrorOr<void> create_font_tab(GUI::TabWidget&, NonnullRefPtr<Core::MappedFile>, StringView mime_type);
-    ErrorOr<void> create_image_tab(GUI::TabWidget&, NonnullRefPtr<Core::MappedFile>, StringView mime_type);
-    ErrorOr<void> create_pdf_tab(GUI::TabWidget&, NonnullRefPtr<Core::MappedFile>);
+    ErrorOr<void> create_archive_tab(GUI::TabWidget&, NonnullOwnPtr<Core::MappedFile>);
+    ErrorOr<void> create_audio_tab(GUI::TabWidget&, NonnullOwnPtr<Core::MappedFile>);
+    ErrorOr<void> create_font_tab(GUI::TabWidget&, NonnullOwnPtr<Core::MappedFile>, StringView mime_type);
+    ErrorOr<void> create_image_tab(GUI::TabWidget&, NonnullOwnPtr<Core::MappedFile>, StringView mime_type);
+    ErrorOr<void> create_pdf_tab(GUI::TabWidget&, NonnullOwnPtr<Core::MappedFile>);
 
     struct PermissionMasks {
         mode_t read;
diff --git a/Userland/Applications/FontEditor/MainWidget.cpp b/Userland/Applications/FontEditor/MainWidget.cpp
index ba2a801a2c4..56b016fb349 100644
--- a/Userland/Applications/FontEditor/MainWidget.cpp
+++ b/Userland/Applications/FontEditor/MainWidget.cpp
@@ -818,7 +818,7 @@ ErrorOr<void> MainWidget::save_file(StringView path, NonnullOwnPtr<Core::File> f
 ErrorOr<void> MainWidget::open_file(StringView path, NonnullOwnPtr<Core::File> file)
 {
     auto mapped_file = TRY(Core::MappedFile::map_from_file(move(file), path));
-    auto unmasked_font = TRY(TRY(Gfx::BitmapFont::try_load_from_mapped_file(mapped_file))->unmasked_character_set());
+    auto unmasked_font = TRY(TRY(Gfx::BitmapFont::try_load_from_mapped_file(move(mapped_file)))->unmasked_character_set());
     TRY(initialize(path, move(unmasked_font)));
     if (!path.is_empty())
         GUI::Application::the()->set_most_recently_open_file(TRY(String::from_utf8(path)));
diff --git a/Userland/Applications/Help/ManualModel.h b/Userland/Applications/Help/ManualModel.h
index 526e8623ce0..a555cbdfe88 100644
--- a/Userland/Applications/Help/ManualModel.h
+++ b/Userland/Applications/Help/ManualModel.h
@@ -42,5 +42,5 @@ private:
     GUI::Icon m_section_open_icon;
     GUI::Icon m_section_icon;
     GUI::Icon m_page_icon;
-    mutable HashMap<String, NonnullRefPtr<Core::MappedFile>> m_mapped_files;
+    mutable HashMap<String, NonnullOwnPtr<Core::MappedFile>> m_mapped_files;
 };
diff --git a/Userland/DevTools/Profiler/DisassemblyModel.cpp b/Userland/DevTools/Profiler/DisassemblyModel.cpp
index 5b4eab557e8..9d8618bd798 100644
--- a/Userland/DevTools/Profiler/DisassemblyModel.cpp
+++ b/Userland/DevTools/Profiler/DisassemblyModel.cpp
@@ -29,7 +29,8 @@ static ELF::Image* try_load_kernel_binary()
     auto kernel_binary_or_error = Core::MappedFile::map("/boot/Kernel"sv);
     if (!kernel_binary_or_error.is_error()) {
         auto kernel_binary = kernel_binary_or_error.release_value();
-        s_kernel_binary = { { kernel_binary, ELF::Image(kernel_binary->bytes()) } };
+        auto image = ELF::Image(kernel_binary->bytes());
+        s_kernel_binary = { { move(kernel_binary), image } };
         return &s_kernel_binary->elf;
     }
     return nullptr;
diff --git a/Userland/DevTools/Profiler/Process.h b/Userland/DevTools/Profiler/Process.h
index f47f7c5d181..064ca69f2b4 100644
--- a/Userland/DevTools/Profiler/Process.h
+++ b/Userland/DevTools/Profiler/Process.h
@@ -17,7 +17,7 @@
 namespace Profiler {
 
 struct MappedObject {
-    NonnullRefPtr<Core::MappedFile> file;
+    NonnullOwnPtr<Core::MappedFile> file;
     ELF::Image elf;
 };
 
diff --git a/Userland/DevTools/Profiler/Profile.cpp b/Userland/DevTools/Profiler/Profile.cpp
index 5fddf4abd3e..f665227c153 100644
--- a/Userland/DevTools/Profiler/Profile.cpp
+++ b/Userland/DevTools/Profiler/Profile.cpp
@@ -280,7 +280,7 @@ ErrorOr<NonnullOwnPtr<Profile>> Profile::load_from_perfcore_file(StringView path
         if (!debuginfo_file_or_error.is_error()) {
             auto debuginfo_file = debuginfo_file_or_error.release_value();
             auto debuginfo_image = ELF::Image(debuginfo_file->bytes());
-            g_kernel_debuginfo_object = { { debuginfo_file, move(debuginfo_image) } };
+            g_kernel_debuginfo_object = { { move(debuginfo_file), move(debuginfo_image) } };
         }
     }
 
diff --git a/Userland/DevTools/UserspaceEmulator/Emulator.h b/Userland/DevTools/UserspaceEmulator/Emulator.h
index f867ea44342..df9f4003ea3 100644
--- a/Userland/DevTools/UserspaceEmulator/Emulator.h
+++ b/Userland/DevTools/UserspaceEmulator/Emulator.h
@@ -286,7 +286,7 @@ private:
     Optional<size_t> m_loader_text_size;
 
     struct CachedELF {
-        NonnullRefPtr<Core::MappedFile> mapped_file;
+        NonnullOwnPtr<Core::MappedFile> mapped_file;
         NonnullOwnPtr<Debug::DebugInfo> debug_info;
         NonnullOwnPtr<ELF::Image> image;
     };
diff --git a/Userland/Libraries/LibCompress/Gzip.cpp b/Userland/Libraries/LibCompress/Gzip.cpp
index 5f23560bd7e..89c779aa4ce 100644
--- a/Userland/Libraries/LibCompress/Gzip.cpp
+++ b/Userland/Libraries/LibCompress/Gzip.cpp
@@ -266,7 +266,7 @@ ErrorOr<void> GzipCompressor::compress_file(StringView input_filename, NonnullOw
 {
     // We map the whole file instead of streaming to reduce size overhead (gzip header) and increase the deflate block size (better compression)
     // TODO: automatically fallback to buffered streaming for very large files
-    RefPtr<Core::MappedFile> file;
+    OwnPtr<Core::MappedFile> file;
     ReadonlyBytes input_bytes;
 
     if (TRY(Core::System::stat(input_filename)).st_size > 0) {
diff --git a/Userland/Libraries/LibCore/MappedFile.cpp b/Userland/Libraries/LibCore/MappedFile.cpp
index af0b5330622..125d5b0c08d 100644
--- a/Userland/Libraries/LibCore/MappedFile.cpp
+++ b/Userland/Libraries/LibCore/MappedFile.cpp
@@ -14,18 +14,18 @@
 
 namespace Core {
 
-ErrorOr<NonnullRefPtr<MappedFile>> MappedFile::map(StringView path)
+ErrorOr<NonnullOwnPtr<MappedFile>> MappedFile::map(StringView path)
 {
     auto fd = TRY(Core::System::open(path, O_RDONLY | O_CLOEXEC, 0));
     return map_from_fd_and_close(fd, path);
 }
 
-ErrorOr<NonnullRefPtr<MappedFile>> MappedFile::map_from_file(NonnullOwnPtr<Core::File> stream, StringView path)
+ErrorOr<NonnullOwnPtr<MappedFile>> MappedFile::map_from_file(NonnullOwnPtr<Core::File> stream, StringView path)
 {
     return map_from_fd_and_close(stream->leak_fd(Badge<MappedFile> {}), path);
 }
 
-ErrorOr<NonnullRefPtr<MappedFile>> MappedFile::map_from_fd_and_close(int fd, [[maybe_unused]] StringView path)
+ErrorOr<NonnullOwnPtr<MappedFile>> MappedFile::map_from_fd_and_close(int fd, [[maybe_unused]] StringView path)
 {
     TRY(Core::System::fcntl(fd, F_SETFD, FD_CLOEXEC));
 
@@ -38,7 +38,7 @@ ErrorOr<NonnullRefPtr<MappedFile>> MappedFile::map_from_fd_and_close(int fd, [[m
 
     auto* ptr = TRY(Core::System::mmap(nullptr, size, PROT_READ, MAP_SHARED, fd, 0, 0, path));
 
-    return adopt_ref(*new MappedFile(ptr, size));
+    return adopt_own(*new MappedFile(ptr, size));
 }
 
 MappedFile::MappedFile(void* ptr, size_t size)
diff --git a/Userland/Libraries/LibCore/MappedFile.h b/Userland/Libraries/LibCore/MappedFile.h
index 7ad2b709f3b..8372c6e4bda 100644
--- a/Userland/Libraries/LibCore/MappedFile.h
+++ b/Userland/Libraries/LibCore/MappedFile.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2023, kleines Filmröllchen <filmroellchen@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -8,20 +9,20 @@
 
 #include <AK/Error.h>
 #include <AK/Noncopyable.h>
-#include <AK/NonnullRefPtr.h>
+#include <AK/NonnullOwnPtr.h>
 #include <AK/RefCounted.h>
 #include <LibCore/Forward.h>
 
 namespace Core {
 
-class MappedFile : public RefCounted<MappedFile> {
+class MappedFile {
     AK_MAKE_NONCOPYABLE(MappedFile);
     AK_MAKE_NONMOVABLE(MappedFile);
 
 public:
-    static ErrorOr<NonnullRefPtr<MappedFile>> map(StringView path);
-    static ErrorOr<NonnullRefPtr<MappedFile>> map_from_file(NonnullOwnPtr<Core::File>, StringView path);
-    static ErrorOr<NonnullRefPtr<MappedFile>> map_from_fd_and_close(int fd, StringView path);
+    static ErrorOr<NonnullOwnPtr<MappedFile>> map(StringView path);
+    static ErrorOr<NonnullOwnPtr<MappedFile>> map_from_file(NonnullOwnPtr<Core::File>, StringView path);
+    static ErrorOr<NonnullOwnPtr<MappedFile>> map_from_fd_and_close(int fd, StringView path);
     ~MappedFile();
 
     void* data() { return m_data; }
@@ -38,4 +39,18 @@ private:
     size_t m_size { 0 };
 };
 
+class SharedMappedFile : public RefCounted<SharedMappedFile> {
+public:
+    explicit SharedMappedFile(NonnullOwnPtr<MappedFile> file)
+        : m_file(move(file))
+    {
+    }
+
+    MappedFile const& operator->() const { return *m_file; }
+    MappedFile& operator->() { return *m_file; }
+
+private:
+    NonnullOwnPtr<MappedFile> m_file;
+};
+
 }
diff --git a/Userland/Libraries/LibCoredump/Backtrace.h b/Userland/Libraries/LibCoredump/Backtrace.h
index 9ce037f3c5f..598cecccec2 100644
--- a/Userland/Libraries/LibCoredump/Backtrace.h
+++ b/Userland/Libraries/LibCoredump/Backtrace.h
@@ -15,14 +15,14 @@
 namespace Coredump {
 
 struct ELFObjectInfo {
-    ELFObjectInfo(NonnullRefPtr<Core::MappedFile> file, NonnullOwnPtr<Debug::DebugInfo>&& debug_info, NonnullOwnPtr<ELF::Image> image)
+    ELFObjectInfo(NonnullOwnPtr<Core::MappedFile> file, NonnullOwnPtr<Debug::DebugInfo>&& debug_info, NonnullOwnPtr<ELF::Image> image)
         : file(move(file))
         , debug_info(move(debug_info))
         , image(move(image))
     {
     }
 
-    NonnullRefPtr<Core::MappedFile> file;
+    NonnullOwnPtr<Core::MappedFile> file;
     NonnullOwnPtr<Debug::DebugInfo> debug_info;
     NonnullOwnPtr<ELF::Image> image;
 };
diff --git a/Userland/Libraries/LibCoredump/Inspector.cpp b/Userland/Libraries/LibCoredump/Inspector.cpp
index b5cae587a26..bad065ab632 100644
--- a/Userland/Libraries/LibCoredump/Inspector.cpp
+++ b/Userland/Libraries/LibCoredump/Inspector.cpp
@@ -47,7 +47,7 @@ void Inspector::parse_loaded_libraries(Function<void(float)> on_progress)
 
         auto image = make<ELF::Image>(file_or_error.value()->bytes());
         auto debug_info = make<Debug::DebugInfo>(*image, DeprecatedString {}, library.base_address);
-        m_loaded_libraries.append(make<Debug::LoadedLibrary>(library.name, file_or_error.value(), move(image), move(debug_info), library.base_address));
+        m_loaded_libraries.append(make<Debug::LoadedLibrary>(library.name, file_or_error.release_value(), move(image), move(debug_info), library.base_address));
     });
 }
 
diff --git a/Userland/Libraries/LibCoredump/Reader.cpp b/Userland/Libraries/LibCoredump/Reader.cpp
index e071f472ad7..42ffb597ac8 100644
--- a/Userland/Libraries/LibCoredump/Reader.cpp
+++ b/Userland/Libraries/LibCoredump/Reader.cpp
@@ -43,7 +43,7 @@ Reader::Reader(ByteBuffer buffer)
     m_coredump_buffer = move(buffer);
 }
 
-Reader::Reader(NonnullRefPtr<Core::MappedFile> file)
+Reader::Reader(NonnullOwnPtr<Core::MappedFile> file)
     : Reader(file->bytes())
 {
     m_mapped_file = move(file);
diff --git a/Userland/Libraries/LibCoredump/Reader.h b/Userland/Libraries/LibCoredump/Reader.h
index e8a754bd5f7..959c8f8c74e 100644
--- a/Userland/Libraries/LibCoredump/Reader.h
+++ b/Userland/Libraries/LibCoredump/Reader.h
@@ -66,7 +66,7 @@ public:
     struct LibraryData {
         DeprecatedString name;
         FlatPtr base_address { 0 };
-        NonnullRefPtr<Core::MappedFile> file;
+        NonnullOwnPtr<Core::MappedFile> file;
         ELF::Image lib_elf;
     };
     LibraryData const* library_containing(FlatPtr address) const;
@@ -83,7 +83,7 @@ public:
 private:
     explicit Reader(ReadonlyBytes);
     explicit Reader(ByteBuffer);
-    explicit Reader(NonnullRefPtr<Core::MappedFile>);
+    explicit Reader(NonnullOwnPtr<Core::MappedFile>);
 
     static Optional<ByteBuffer> decompress_coredump(ReadonlyBytes);
 
@@ -108,7 +108,7 @@ private:
     const JsonObject process_info() const;
 
     // For uncompressed coredumps, we keep the MappedFile
-    RefPtr<Core::MappedFile> m_mapped_file;
+    OwnPtr<Core::MappedFile> m_mapped_file;
 
     // For compressed coredumps, we decompress them into a ByteBuffer
     ByteBuffer m_coredump_buffer;
diff --git a/Userland/Libraries/LibDebug/LoadedLibrary.h b/Userland/Libraries/LibDebug/LoadedLibrary.h
index 47580b00c13..658b31b435e 100644
--- a/Userland/Libraries/LibDebug/LoadedLibrary.h
+++ b/Userland/Libraries/LibDebug/LoadedLibrary.h
@@ -14,12 +14,12 @@
 namespace Debug {
 struct LoadedLibrary {
     DeprecatedString name;
-    NonnullRefPtr<Core::MappedFile> file;
+    NonnullOwnPtr<Core::MappedFile> file;
     NonnullOwnPtr<ELF::Image> image;
     NonnullOwnPtr<DebugInfo> debug_info;
     FlatPtr base_address {};
 
-    LoadedLibrary(DeprecatedString const& name, NonnullRefPtr<Core::MappedFile> file, NonnullOwnPtr<ELF::Image> image, NonnullOwnPtr<DebugInfo>&& debug_info, FlatPtr base_address)
+    LoadedLibrary(DeprecatedString const& name, NonnullOwnPtr<Core::MappedFile> file, NonnullOwnPtr<ELF::Image> image, NonnullOwnPtr<DebugInfo>&& debug_info, FlatPtr base_address)
         : name(name)
         , file(move(file))
         , image(move(image))
diff --git a/Userland/Libraries/LibGfx/Font/BitmapFont.cpp b/Userland/Libraries/LibGfx/Font/BitmapFont.cpp
index 4aae9858d33..28ae2f04347 100644
--- a/Userland/Libraries/LibGfx/Font/BitmapFont.cpp
+++ b/Userland/Libraries/LibGfx/Font/BitmapFont.cpp
@@ -239,10 +239,10 @@ ErrorOr<NonnullRefPtr<BitmapFont>> BitmapFont::try_load_from_file(DeprecatedStri
     return try_load_from_mapped_file(move(mapped_file));
 }
 
-ErrorOr<NonnullRefPtr<BitmapFont>> BitmapFont::try_load_from_mapped_file(RefPtr<Core::MappedFile> const& mapped_file)
+ErrorOr<NonnullRefPtr<BitmapFont>> BitmapFont::try_load_from_mapped_file(OwnPtr<Core::MappedFile> mapped_file)
 {
     auto font = TRY(load_from_memory((u8 const*)mapped_file->data()));
-    font->m_mapped_file = mapped_file;
+    font->m_mapped_file = move(mapped_file);
     return font;
 }
 
diff --git a/Userland/Libraries/LibGfx/Font/BitmapFont.h b/Userland/Libraries/LibGfx/Font/BitmapFont.h
index 8f7c5e22e1f..fba06b3308f 100644
--- a/Userland/Libraries/LibGfx/Font/BitmapFont.h
+++ b/Userland/Libraries/LibGfx/Font/BitmapFont.h
@@ -32,7 +32,7 @@ public:
 
     static RefPtr<BitmapFont> load_from_file(DeprecatedString const& path);
     static ErrorOr<NonnullRefPtr<BitmapFont>> try_load_from_file(DeprecatedString const& path);
-    static ErrorOr<NonnullRefPtr<BitmapFont>> try_load_from_mapped_file(RefPtr<Core::MappedFile> const&);
+    static ErrorOr<NonnullRefPtr<BitmapFont>> try_load_from_mapped_file(OwnPtr<Core::MappedFile>);
 
     ErrorOr<void> write_to_file(DeprecatedString const& path);
     ErrorOr<void> write_to_file(NonnullOwnPtr<Core::File> file);
@@ -156,7 +156,7 @@ private:
 
     u8* m_rows { nullptr };
     u8* m_glyph_widths { nullptr };
-    RefPtr<Core::MappedFile> m_mapped_file;
+    OwnPtr<Core::MappedFile> m_mapped_file;
 
     u8 m_glyph_width { 0 };
     u8 m_glyph_height { 0 };
diff --git a/Userland/Libraries/LibGfx/Font/OpenType/Font.h b/Userland/Libraries/LibGfx/Font/OpenType/Font.h
index fb0a32ab20b..b2b7f4cd671 100644
--- a/Userland/Libraries/LibGfx/Font/OpenType/Font.h
+++ b/Userland/Libraries/LibGfx/Font/OpenType/Font.h
@@ -107,7 +107,7 @@ private:
     {
     }
 
-    RefPtr<Core::MappedFile> m_mapped_file;
+    OwnPtr<Core::MappedFile> m_mapped_file;
 
     ReadonlyBytes m_buffer;
 
diff --git a/Userland/Libraries/LibPCIDB/Database.h b/Userland/Libraries/LibPCIDB/Database.h
index 9353578bcfd..fbc714b1ef8 100644
--- a/Userland/Libraries/LibPCIDB/Database.h
+++ b/Userland/Libraries/LibPCIDB/Database.h
@@ -64,7 +64,7 @@ public:
     const StringView get_programming_interface(u8 class_id, u8 subclass_id, u8 programming_interface_id) const;
 
 private:
-    explicit Database(NonnullRefPtr<Core::MappedFile> file)
+    explicit Database(NonnullOwnPtr<Core::MappedFile> file)
         : m_file(move(file))
     {
     }
@@ -77,7 +77,7 @@ private:
         ClassMode,
     };
 
-    NonnullRefPtr<Core::MappedFile> m_file;
+    NonnullOwnPtr<Core::MappedFile> m_file;
     StringView m_view {};
     HashMap<int, NonnullOwnPtr<Vendor>> m_vendors;
     HashMap<int, NonnullOwnPtr<Class>> m_classes;
diff --git a/Userland/Libraries/LibSymbolication/Symbolication.cpp b/Userland/Libraries/LibSymbolication/Symbolication.cpp
index 29afeb7ed0d..d2c0cff7656 100644
--- a/Userland/Libraries/LibSymbolication/Symbolication.cpp
+++ b/Userland/Libraries/LibSymbolication/Symbolication.cpp
@@ -19,7 +19,7 @@
 namespace Symbolication {
 
 struct CachedELF {
-    NonnullRefPtr<Core::MappedFile> mapped_file;
+    NonnullOwnPtr<Core::MappedFile> mapped_file;
     NonnullOwnPtr<Debug::DebugInfo> debug_info;
     NonnullOwnPtr<ELF::Image> image;
 };
diff --git a/Userland/Libraries/LibUSBDB/Database.h b/Userland/Libraries/LibUSBDB/Database.h
index 5f0e297df01..b0028fb83ae 100644
--- a/Userland/Libraries/LibUSBDB/Database.h
+++ b/Userland/Libraries/LibUSBDB/Database.h
@@ -63,7 +63,7 @@ public:
     const StringView get_protocol(u8 class_id, u8 subclass_id, u8 protocol_id) const;
 
 private:
-    explicit Database(NonnullRefPtr<Core::MappedFile> file)
+    explicit Database(NonnullOwnPtr<Core::MappedFile> file)
         : m_file(move(file))
     {
     }
@@ -76,7 +76,7 @@ private:
         ClassMode,
     };
 
-    NonnullRefPtr<Core::MappedFile> m_file;
+    NonnullOwnPtr<Core::MappedFile> m_file;
     StringView m_view {};
     HashMap<int, NonnullOwnPtr<Vendor>> m_vendors;
     HashMap<int, NonnullOwnPtr<Class>> m_classes;
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp b/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp
index c2b873031b7..a45a9cb74c8 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp
@@ -14,7 +14,7 @@ DecoderErrorOr<NonnullOwnPtr<MatroskaDemuxer>> MatroskaDemuxer::from_file(String
     return make<MatroskaDemuxer>(TRY(Reader::from_file(filename)));
 }
 
-DecoderErrorOr<NonnullOwnPtr<MatroskaDemuxer>> MatroskaDemuxer::from_mapped_file(NonnullRefPtr<Core::MappedFile> mapped_file)
+DecoderErrorOr<NonnullOwnPtr<MatroskaDemuxer>> MatroskaDemuxer::from_mapped_file(NonnullOwnPtr<Core::MappedFile> mapped_file)
 {
     return make<MatroskaDemuxer>(TRY(Reader::from_mapped_file(move(mapped_file))));
 }
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.h b/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.h
index 225ebed06fc..59bd151a278 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.h
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.h
@@ -18,7 +18,7 @@ public:
     // FIXME: We should instead accept some abstract data streaming type so that the demuxer
     //        can work with non-contiguous data.
     static DecoderErrorOr<NonnullOwnPtr<MatroskaDemuxer>> from_file(StringView filename);
-    static DecoderErrorOr<NonnullOwnPtr<MatroskaDemuxer>> from_mapped_file(NonnullRefPtr<Core::MappedFile> mapped_file);
+    static DecoderErrorOr<NonnullOwnPtr<MatroskaDemuxer>> from_mapped_file(NonnullOwnPtr<Core::MappedFile> mapped_file);
 
     static DecoderErrorOr<NonnullOwnPtr<MatroskaDemuxer>> from_data(ReadonlyBytes data);
 
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
index 9d6ca54a18d..e5091ee2d3e 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
@@ -86,13 +86,13 @@ constexpr u32 CUE_REFERENCE_ID = 0xDB;
 DecoderErrorOr<Reader> Reader::from_file(StringView path)
 {
     auto mapped_file = DECODER_TRY(DecoderErrorCategory::IO, Core::MappedFile::map(path));
-    return from_mapped_file(mapped_file);
+    return from_mapped_file(move(mapped_file));
 }
 
-DecoderErrorOr<Reader> Reader::from_mapped_file(NonnullRefPtr<Core::MappedFile> mapped_file)
+DecoderErrorOr<Reader> Reader::from_mapped_file(NonnullOwnPtr<Core::MappedFile> mapped_file)
 {
     auto reader = TRY(from_data(mapped_file->bytes()));
-    reader.m_mapped_file = move(mapped_file);
+    reader.m_mapped_file = make_ref_counted<Core::SharedMappedFile>(move(mapped_file));
     return reader;
 }
 
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.h b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.h
index 80cf336e43e..6c7e352adee 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.h
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.h
@@ -25,7 +25,7 @@ public:
     typedef Function<DecoderErrorOr<IterationDecision>(TrackEntry const&)> TrackEntryCallback;
 
     static DecoderErrorOr<Reader> from_file(StringView path);
-    static DecoderErrorOr<Reader> from_mapped_file(NonnullRefPtr<Core::MappedFile> mapped_file);
+    static DecoderErrorOr<Reader> from_mapped_file(NonnullOwnPtr<Core::MappedFile> mapped_file);
 
     static DecoderErrorOr<Reader> from_data(ReadonlyBytes data);
 
@@ -60,7 +60,7 @@ private:
     DecoderErrorOr<void> ensure_cues_are_parsed();
     DecoderErrorOr<void> seek_to_cue_for_timestamp(SampleIterator&, Duration const&);
 
-    RefPtr<Core::MappedFile> m_mapped_file;
+    RefPtr<Core::SharedMappedFile> m_mapped_file;
     ReadonlyBytes m_data;
 
     Optional<EBMLHeader> m_header;
@@ -89,7 +89,7 @@ public:
 private:
     friend class Reader;
 
-    SampleIterator(RefPtr<Core::MappedFile> file, ReadonlyBytes data, TrackEntry track, u64 timestamp_scale, size_t position)
+    SampleIterator(RefPtr<Core::SharedMappedFile> file, ReadonlyBytes data, TrackEntry track, u64 timestamp_scale, size_t position)
         : m_file(move(file))
         , m_data(data)
         , m_track(move(track))
@@ -100,7 +100,7 @@ private:
 
     DecoderErrorOr<void> seek_to_cue_point(CuePoint const& cue_point);
 
-    RefPtr<Core::MappedFile> m_file;
+    RefPtr<Core::SharedMappedFile> m_file;
     ReadonlyBytes m_data;
     TrackEntry m_track;
     u64 m_segment_timestamp_scale { 0 };
diff --git a/Userland/Libraries/LibVideo/PlaybackManager.cpp b/Userland/Libraries/LibVideo/PlaybackManager.cpp
index 45524d33082..8ef34ef3f8f 100644
--- a/Userland/Libraries/LibVideo/PlaybackManager.cpp
+++ b/Userland/Libraries/LibVideo/PlaybackManager.cpp
@@ -31,7 +31,7 @@ DecoderErrorOr<NonnullOwnPtr<PlaybackManager>> PlaybackManager::from_file(String
     return create(move(demuxer));
 }
 
-DecoderErrorOr<NonnullOwnPtr<PlaybackManager>> PlaybackManager::from_mapped_file(NonnullRefPtr<Core::MappedFile> mapped_file)
+DecoderErrorOr<NonnullOwnPtr<PlaybackManager>> PlaybackManager::from_mapped_file(NonnullOwnPtr<Core::MappedFile> mapped_file)
 {
     auto demuxer = TRY(Matroska::MatroskaDemuxer::from_mapped_file(move(mapped_file)));
     return create(move(demuxer));
diff --git a/Userland/Libraries/LibVideo/PlaybackManager.h b/Userland/Libraries/LibVideo/PlaybackManager.h
index b35d770b6c9..f3a5bf7a941 100644
--- a/Userland/Libraries/LibVideo/PlaybackManager.h
+++ b/Userland/Libraries/LibVideo/PlaybackManager.h
@@ -112,7 +112,7 @@ public:
     static constexpr SeekMode DEFAULT_SEEK_MODE = SeekMode::Accurate;
 
     static DecoderErrorOr<NonnullOwnPtr<PlaybackManager>> from_file(StringView file);
-    static DecoderErrorOr<NonnullOwnPtr<PlaybackManager>> from_mapped_file(NonnullRefPtr<Core::MappedFile> file);
+    static DecoderErrorOr<NonnullOwnPtr<PlaybackManager>> from_mapped_file(NonnullOwnPtr<Core::MappedFile> file);
 
     static DecoderErrorOr<NonnullOwnPtr<PlaybackManager>> from_data(ReadonlyBytes data);
 
diff --git a/Userland/Utilities/disasm.cpp b/Userland/Utilities/disasm.cpp
index a8985bd7448..1b00c6aa349 100644
--- a/Userland/Utilities/disasm.cpp
+++ b/Userland/Utilities/disasm.cpp
@@ -29,7 +29,7 @@ ErrorOr<int> serenity_main(Main::Arguments args)
     args_parser.add_positional_argument(path, "Path to i386 binary file", "path");
     args_parser.parse(args);
 
-    RefPtr<Core::MappedFile> file;
+    OwnPtr<Core::MappedFile const> file;
     u8 const* asm_data = nullptr;
     size_t asm_size = 0;
     if ((TRY(Core::System::stat(path))).st_size > 0) {
diff --git a/Userland/Utilities/fdtdump.cpp b/Userland/Utilities/fdtdump.cpp
index 481bd448a3f..b49e869ca8e 100644
--- a/Userland/Utilities/fdtdump.cpp
+++ b/Userland/Utilities/fdtdump.cpp
@@ -31,7 +31,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     }
 
     auto const* fdt_header = reinterpret_cast<DeviceTree::FlattenedDeviceTreeHeader const*>(file->data());
-    auto bytes = ReadonlyBytes { file->data(), file->size() };
+    auto bytes = file->bytes();
 
     TRY(DeviceTree::dump(*fdt_header, bytes));
 
diff --git a/Userland/Utilities/image.cpp b/Userland/Utilities/image.cpp
index 4af25a94dda..7fc97e2eb68 100644
--- a/Userland/Utilities/image.cpp
+++ b/Userland/Utilities/image.cpp
@@ -116,7 +116,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     Optional<ReadonlyBytes> icc_data = TRY(decoder->icc_data());
 
-    RefPtr<Core::MappedFile> icc_file;
+    OwnPtr<Core::MappedFile> icc_file;
     if (!assign_color_profile_path.is_empty()) {
         icc_file = TRY(Core::MappedFile::map(assign_color_profile_path));
         icc_data = icc_file->bytes();
@@ -128,7 +128,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             return 1;
         }
 
-        auto source_icc_file = icc_file;
+        auto source_icc_file = move(icc_file);
         auto source_icc_data = icc_data.value();
         icc_file = TRY(Core::MappedFile::map(convert_color_profile_path));
         icc_data = icc_file->bytes();
diff --git a/Userland/Utilities/unzip.cpp b/Userland/Utilities/unzip.cpp
index 49964413448..440ba687bf6 100644
--- a/Userland/Utilities/unzip.cpp
+++ b/Userland/Utilities/unzip.cpp
@@ -122,7 +122,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     // FIXME: Map file chunk-by-chunk once we have mmap() with offset.
     //        This will require mapping some parts then unmapping them repeatedly,
     //        but it would be significantly faster and less syscall heavy than seek()/read() at every read.
-    RefPtr<Core::MappedFile> mapped_file;
+    OwnPtr<Core::MappedFile> mapped_file;
     ReadonlyBytes input_bytes;
     if (st.st_size > 0) {
         mapped_file = TRY(Core::MappedFile::map(zip_file_path));