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- Lapak: from the novel Alaska by James A. Michener
- Lavalava Island: from the video game Paper Mario
- Lea Monde: from the video game Vagrant Story
- Leap Islands: from The Monikins by James Fenimore Cooper
- LEGO Island: from the video games LEGO Island, LEGO Island 2: The Brickster's Revenge and Island Xtreme Stunts.
- Leshp: from Discworld series by Terry Pratchett
- Lilliput: from the novel Gulliver's Travels by Jonathan Swift
- Lincoln Island: from Jules Verne's novel The Mysterious Island
- Lingshe Island: in the novel The Heavenly Sword and the Dragon Saber by Jinyong
- Little Todday (Todaidh Beag): an island in the Hebrides, companion of Great Todday in the novel Whisky Galore by Compton Mackenzie
- Lucre Island: a pirate island in the game Escape from Monkey Island
- Lutari Island: an island in Neopia
Read more about this topic: List Of Fictional Islands