Man Arm mostly resembles a large humanoid alligator. His right arm is large and muscular, with a tattoo of an arrowed heart on his right shoulder, while his left arm is stubby, and looks like that of a normal human. Man Arm's body is mostly green (except for his left arm), and he has yellow eyes and grayish blue spikes running down his back and tail. He also wears a black wristband on his right arm, black shorts, and black boots.
Man Arm first appears in "Cheer Up, Star", where he attacks Star Butterfly and Marco Diaz. He is the one who pulls Marco out of the shed, with Star following after him. Man-Arm is introduced to them because Marco claims to have never seen him before in earlier fights.
In "Storm the Castle", he attacks Star after her first attempt to destroy Marco's crystal prison, but he is then attacked by Buff Frog. He greets his old comrade pleasantly, but Buff Frog punches him in the face, knocking him out.
Click here to view the gallery.