Ukkiki is a character from the video game Super Mario 64. Ukkiki is a monkey, and has a penchant for stealing the hat of the game's playable character, Mario. Ukkiki lives on Tall, Tall Mountain, which in the game is the twelfth of fifteen courses. Like all courses in Super Mario 64, Tall, Tall Mountain has seven playable tasks, and Ukkiki the monkey is directly involved in one of them. In this challenge, Mario finds that the treasure he came to acquire is locked in a cage, and the only way to open is to retrieve a key to open it, the only one that can do this is in the possession of Ukkiki, who lives on the mountain summit. After retrieving the key, Ukkiki spends his time stealing Mario's hat.

Ukkiki appers in other video games from the Mario series, including some of those from the Mario Party series. He usually plays a part in throwing bananas onto the game board during play, or interfering in mini-games in such a manner. He does not engage in hat-stealing activities in the Mario Party games, however.