Monkey Yellow (ウッキーイエロー Ukī Ierō?) is the extremely fat, as well as disturbing, member of the Freaky Monkey 5. He first appeared in Ape Escape 2. When he eats more Vita-Z bananas than he's supposed to, he can grow to sizes equal to that of a skyscraper's. When he did, Hikaru had to fight him by waiting for him to do a rush attack, then knocking his rotten teeth out with the stun club. In P&P, he is referred through a fan letter, saying that he needs false teeth. He reappears in AE3 as a ninja, reprising his role as a Freaky Monkey Five member. In the Ape Escape anime, he is dressed as a chef and carries a giant fork with him. (This could be a reference to Final Fantasy IX's Quina Quen, a genderless creature much like Yellow Monkey a male who would love to be female).
Yellow Monkey is very strong, though nowhere near as strong as Red Monkey, and despite his size and build he is actually very swift. Yellow Monkey is one of the most interesting members of the FMF, as he is the only member whose body color is the same as in his name (excluding Pink and White) and his physical appearance has been changed so much that he's barely even noticeable as a monkey. This may be in part due to Vita-Z bananas, which seem to have increased his size greatly. This is revealed when you defeat his giant form in the second game, and he is shrunk to the point where he's almost smaller than Pipotchi. Though it's revealed that Yellow Monkey is a male, it should be noted that he has an extremely feminine voice. In Ape Escape Academy, his name is Ukki Yellow. In rank of strength, Yellow Monkey lies within the range of third strongest. His different styles of fighting help keep a battle going, but he doesn't have as many attacks as Pink or Red.