Roberto (voiced by David Herman) is a criminally insane, psychotic robot who often carries a knife with which he is prone to stabbing. His voice is based on that of comedian Dick Shawn. He is often depicted as a patient receiving treatment for criminal insanity. In his first appearance in " Insane in the Mainframe ", he is committed to an insane asylum after he targets the same bank for robbery three times in a row, and is seen killing other robots when escaping that hospital. In Bender's Game he states that his creators were trying to make an insane robot, but "failed". This violent nature is enhanced by a body that David X. Cohen and Matt Groening say is based on the shape of a tombstone. Roberto appears in Bender's Game as a patient in the same asylum. He later appears in the Middle-earth spoof scenes of that film as a role equivalent to that of Denethor. He briefly becomes sane after he is hit on the head during a battle, but reverts to insanity after he is immediately hit a second time. He appears in " Proposition Infinity " in the same asylum, this time with a sock instead of his usual knife. He says to Bender, "You ever kill a man with a sock? It ain't so hard."