Alvin the Treacherous is an anti-hero of Dreamworks Dragons: Riders of Berk and DreamWorks: Defenders of Berk. Though intially a villain, he slowly develops a change of heart, best shown as he later saves Snotlout from the Screaming Death, who is charged with several forms of treachery and is locked up. Alvin tries to propose a deal with Stoick and Hiccup about reclaiming his island from Dagur and having the Outcasts allies to Berk, though they refuse. Snotlout later checks on him, and Alvin says the two of them are a lot alike. When the warning call sounds, Snotlout lets Alvin out to help. He even assits Stoick in the fight. When Stoick is captured, Alvin convinces Hiccup not to go after Dagur. He is later locked up again by Snotlout.
In the next episode, Alvin and Hiccup work together to save Stoick. After his heroic act, Alvin redeems himself and possibly becomes an ally of Berk.
He is Voiced by Mark Hamill.