Uncle Leo is a fictional character portrayed by Len Lesser in the American sitcom Seinfeld. Leo is the character Jerry Seinfeld's uncle. Uncle Leo made his debut in the second-season episode "The Pony Remark" and appeared in at least one episode in each of the subsequent seasons through the show's nine-season run. On the 25th anniversary of the show's debut, Rolling Stone ranked Uncle Leo as number six on its list of "100 Best Seinfeld Characters," behind only Newman at number five and the four main characters: Jerry, Kramer, Elaine, and George.