Gilligan's buddy on Gilligan's Island. His "real" name on the show was Jonas Grumby, but no one called him that. After the show went off the air, Alan Hale continued to appear in character at his Los Angeles restaurant, "Alan Hale's Lobster Barrel."
I'm going with the Skipper as a sidekick purely because the show was named after Gilligan. It could go either way, don't you think?