Sideshow Mel, full name Melvin van Horne, is a minor cartoon character on the TV show The Simpsons. Sideshow Mel has served as Krusty the Clown's sidekick for more than a decade, replacing Sideshow Bob after Bob was incarcerated from framing Krusty for robbery.

Little is known about Mel. He is a Cornell University graduate. He may be named for Roy Van Horn, half of the famous Las Vegas lounge act Siegfried and Roy.

Sideshow Mel uses a slide whistle to communicate on camera. When not in character, Mel speaks in a grandiose British/Shakespearean accent. His main accomplishment so far has been successfully removing Waylon Smithers from suspicion of having shot Mr. Burns.

Bart Simpson has found out that Mel is lactose intolerant. Mel perpetually wears a bone in his hair which may or may not be permanently affixed: once he claimed it was stuck there with gum, but elsewhere he removed and used it as a weapon during a duel. He may be married or living with a woman, who may or may not be Krusty's sister, with whom he wished to purchase a house from Marge Simpson in the episode "Reality Bites" (he declined, disliking the bowling alley feature).