Guenter (voiced by Tress MacNeille, vocal effects provided by Frank Welker) is an intelligent monkey experiment made by Professor Farnsworth. His intelligence comes from his small hat which uses sunspots to create cognitive radiation. If he is not wearing the hat, he acts like a normal monkey. His first appearance was in the episode " Mars University " in which the Professor enrolls him at the university where he becomes Fry 's roommate. Guenter later appears in the episode, "Fry and Leela's Big Fling", where he shows Amy Wong, Bender and Zoidberg around the planet Simian 7. Guenter is seen in other episodes in the background, and crowds.