Beorn is the Tolkien character who can transform between human and bear forms in The Hobbit.
Bilbo and the Dwarves meet Beorn after escaping the Goblins and Wargs. He lives in a large house between the Misty Mountains and Mirkwood, where he keeps animals and provides the travelers with food, shelter, and advice.
Beorn’s ability is described as a skin-changing power. In human form he is a huge, formidable man; in bear form he becomes a powerful creature capable of changing the course of the Battle of Five Armies. His name is connected with Old English and related Germanic words associated with a man or warrior, and Tolkien uses that linguistic background in shaping the character.
Beorn is sometimes confused with other animal-associated figures in Tolkien’s legendarium. Radagast is a wizard linked with birds and beasts, while Gwaihir is a great eagle; neither is a human-to-bear shape-shifter.