Fisty is a frog in World of Goo. He is introduced in the Chapter 1 level Fisty's Bog. A Black Goo structure emerges from his mouth, resembling a tongue. According to the Sign Painter, Fisty "swore he would never be like those tadpoles that grow up and shoot colored gems out of their mouths", referring to the video game known as Zuma.
Kyle Gabler said that Fisty had been in many early advertisements for the game, and had somehow become their, big, slimy, depressed mascot. His relationship with another frog named Misty is unknown, but was clued in Chapter 3, that Fisty had "...thought he saw someone and hoped they could be friends."