Underdog is an anthropomorphic dog, who is a superhero parody of Superman and similar heroes with secret identities. The premise was that "humble and lovable" Shoeshine Boy, a cartoon dog, was in truth the superhero Underdog. When villains threatened, Shoeshine Boy ducked into a telephone booth where he transformed into the caped and costumed hero, destroying the booth in the process when his superpowers were activated. In the live action film, he appeared as a beagle who became Jack Unger's pet. In 2008, he appeared in a Super Bowl advertisement for Coca-Cola.
Underdog is voiced by Wally Cox in the television cartoon. In the film adaptation, he is voiced by Jason Lee and portrayed onscreen by a lemon beagle named Leo sporting a red sweater and a blue cape.
