Gollum, Bilbo, and Frodo definitely have, but who else has worn the one ring in its time?
Five individuals are known to have worn the One Ring:
When did Tom Bombadil wear it?
@Dungeonwyrm In the house of Tom Bombadil when Frodo allowed him to examine the Ring (it had no effect on him). Tom and his wife Goldberry were left out of the movies.
Isildur wore the One Ring to try to escape the Orcs during the Disaster of the Gladden Fields. The ring slipped from his finger as he was swimming in the Anduin, and he was shot with many arrows. The ring stayed in the bottom of the Anduin until Deagol found it. Of course, Deagol was promptly murdered before he had a chance to wear it.