Ukiki

"Ook...Oookiii (I used your capsules!)"

- Ukiki

Ukikis, also known as Ukkikis or Monkeys, first appeared in Super Mario 64, where

Super Mario 64
In Super Mario 64, two Ukiki inhabit Tall, Tall Mountain. One can be seen following Mario around and doing tricks. However, if Mario grabs him, he will steal Mario's hat and wear it. To get it back, Mario has to grab him again; this is made difficult by the fact that Ukiki now runs away from the plumber. In the second mission of Tall, Tall Mountain, Mario has to catch a different Ukiki on the very top of the mountain; when caught, the monkey will jump on a cage with a star for Mario, making it accessible.

Super Mario 64 DS
In the remake Super Mario 64 DS, if any character was wearing another character's hat, the monkey would take it and the character would transform back into himself. A glitch allowed Wario to pick up Ukiki using the Metal Cap and could even carry him into the water.

Mario Party 4
In Mario Party 4, they toss a banana, which, upon being slipped on, will determine a character's path around the game board.

Mario Party 5
In Mario Party 5 they were revealed to also come in other colors: gray, blue, red and very rare gold ones. They had their own capsule as well: when activated, the Ukiki would use all of another character's capsules.

Mario Party 6
In Mario Party 6 Ukiki appeared in Castaway Bay hosting a special coin collecting mini game. They also appeared in various minigames such as Snow Brawl and Strawberry Shortfuse.

Mario Party 7
In Mario Party 7 (where they looked like Grinders), Ukikis cameoed in the background of the Mini-game Cruise, cleaning Peach's Cruiser.

Mario Party 8
In Mario Party 8, Ukikis appeared in DK's Treetop Temple, where they would roll down the stage on barrels, taking ten coins from anyone in their path. Mechanical Ukikis appeared in the mini-game Flip the Chimp. Also in the battle mini-game Snipe for the Picking there are two Ukikis turning cranks.

Mario Party Advance
In Mario Party Advance, a female Ukiki named Akiki (who happens to be the niece of an individual Ukiki who is named "Ukiki") appears.

Mario Power Tennis
Ukikis also have a place in Mario sports titles; like Mario Power Tennis, where they appear in the background of a court.

Mario Strikers Charged Football
They can also be seen in the audiences of Mario Strikers Charged Football.

Mario Baseball series
Ukikis also appear as part of the audience in the Mario Baseball series.

Trivia

 * Ukiki resembles the similarly named monkey from.