In the fictional writings of J. R. R. Tolkien, the Undying Lands are a realm inhabited by immortal beings. It includes Valinor and the island of Tol Eressëa.

The treacherous Sauron deceived the last king of Númenor into thinking the ruler of the Undying Lands would himself be undying, and the king prepared to invade. To prevent this, the divine Ilúvatar destroyed Númenor and placed the undying lands beyond the reach of mortals, although elves could still sail there. A few others have been said to have made the journey in the company of elves by special arrangement: the wizard Gandalf, the Hobbits Bilbo Baggins, Frodo Baggins and Sam Gamgee and the dwarf Gimli.