Isildur cut the One Ring from Sauron’s hand in J.R.R. Tolkien’s legendarium.
During the War of the Last Alliance at the end of the Second Age, Isildur used the hilt-shard of his father Elendil’s sword, Narsil, to cut the Ring from Sauron’s hand. This caused Sauron’s physical defeat, although the Ring survived.
Isildur claimed the Ring rather than destroying it. While traveling north, he was ambushed by Orcs near the Gladden Fields, and the Ring slipped from his finger as he tried to escape through the river. He was then shot and killed.
This event is distinct from the Ring’s destruction at Mount Doom, which occurs much later. Elendil and Gil-galad fought Sauron, but Isildur was the one who severed the Ring from him.