Which Tolkien character first finds the One Ring in The Hobbit?

Bilbo Baggins first finds the One Ring in The Hobbit.

During his journey beneath the Misty Mountains, Bilbo becomes separated from Thorin’s company and encounters Gollum beside an underground lake. While searching in the darkness, Bilbo finds a small golden ring and keeps it. He does not initially understand that it is the One Ring created by Sauron.

Bilbo later uses the ring’s power of invisibility to escape Gollum and return to the dwarves. In The Hobbit, the object is presented primarily as a useful magical ring. The Lord of the Rings later reveals its larger history, its connection to Sauron, and the danger it poses to its bearer.

Frodo Baggins inherits the ring from Bilbo, but Frodo is not its first finder. Gollum possesses it before Bilbo, yet Bilbo is the character who discovers it in the events of The Hobbit.