 Kenny 's superhero alter ego , Mysterion , first appeared in the Season 13 episode " The Coon " , as a rival to Eric Cartman 's eponymous superhero alter ego . He unmasks himself at the end of the episode , but his identity is left intentionally ambiguous . He is not revealed to be Kenny until the Season 14 episode " Mysterion Rises " , the character 's third appearance as part of a story arc . 
