Cappy is a main supporting character in Super Mario Odyssey and Mario’s companion throughout the adventure. He is a sentient hat from the Cap Kingdom who joins Mario after their worlds are threatened by Bowser. Cappy helps Mario by allowing him to capture and control enemies and objects, which is central to the game’s mechanics. He also serves as a guide, story companion, and a key member of the team working to rescue Princess Peach and Cappy’s sister, Tiara.