"Fastitocalon" is a poem by J. R. R. Tolkien about a beast of the same name. The setting is Middle-earth. It is included in The Adventures of Tom Bombadil, and told a similar story to that of The Whale. As such, Tolkien imported the traditional tale of the aspidochelone into the lore of his Middle-earth.
Fastitocalon, the central character, is the last of the mighty turtle-fish. This poem is well-known to the Hobbits. It tells of how Fastitocalon's huge size enticed sailors to land on its back. After the sailors lit a fire upon Fastitocalon, it dove underwater, causing the sailors to drown.
The Fastitocalon was the size of a small island and vegetation would often grow on its back when not submerged, adding to the illusion that it was an actual island.
It is never explained whether the turtle-fish were an actual race in Middle-earth or fictional characters created solely for the poem. It is distinctly possible that the story is in fact an allegory of the fall of Númenor. Like the Fastitocalon, Númenor too sank below the waves, and drowned most of its inhabitants.
Fastitocalon's are an enemy in the video game Final Fantasy VIII. A smaller version, Fastitocalon-F also appears in the game.
In the manga series MÄR, Dorothy fights a puppet named Pinocchio who uses an ÄRM called Fastitocalon.