Sakko is a tiny monkey who acts as a spy for Skeleton King. He was originally presumed to be Jinmay's pet in the first episode, but he pins her down and opens up her chest, revealing that she is a robot. He fails Skeleton King and is taken away by a strange jack in the box looking robot with legs, but he appears in later episodes and with an eyepatch. He makes a brief cameo in the final episode with Krinkle, drawing a picture of the Skeleton King holding him, he says joyfully. He is voiced by Tom Kenny.