Alvin the Treacherous is one of the main antagonists turned supporting protagonist in the How to Train Your Dragon franchise. He is the arch enemy turned ally of Stoick the Vast, Hiccup Haddock and the Dragon Riders.
He was voiced by Mark Hamill, who also played Kavaxas in Tales of the Teenage Mutant Ninja Turtles, Colonel Muska in Castle in the Sky, and the Joker in Batman: The Animated Series and the Batman: Arkham videogames, the Skeleton King in Super Robot Monkey Team Hyper Force Go!, Maximus in the Fantastic Four animated series, the Hobgoblin in Spider-Man: The Animated Series, Stickybeard in Codename: Kids Next Door, Flint in Disney's Buzz Lightyear of Star Command, Niju in Balto II: Wolf Quest by Universal Pictures, Solomon Grundy in the DC Animated Universe, Fire Lord Ozai in Avatar: The Last Airbender, Trickster in The Flash, Dictatious Maximus Galadrigal in Trollhunters, ShiverJack in Disney's Jake and the Never Land Pirates, Undergrowth in the Danny Phantom series, Agent Goodman in Disney's Recess: School's Out, and Popsicles in the 2016 reiteration of The Powerpuff Girls.