Sheen Juarrera Estevez is one of the main characters from the Nickelodeon animated series The Adventures of Jimmy Neutron, Boy Genius. He is Jimmy Neutron's close friend who is obsessed with the television show UltraLord and, in the later half of the show's run, develops a crush on his classmate Libby Folfax. He would later star in his own spin-off series, Planet Sheen.
In "Nightmare in Retroville", Sheen unintentionally turned into a real werewolf.