Isildur is a fictional character from J.R.R. Tolkien's legendarium, primarily featured in "The Lord of the Rings" and "The Silmarillion." He is a noble man of the race of Dúnedain and the son of Elendil. Isildur is known for his role in the defeat of the Dark Lord Sauron during the War of the Last Alliance. After Sauron's defeat, Isildur claimed the One Ring for himself, which was forged by Sauron to control the other Rings of Power. His decision to keep the Ring ultimately led to his downfall, as he was later ambushed and killed by Orcs while trying to return to his kingdom of Gondor.