Underdog is the name of an anthropomorphic cartoon dog featured in both TV cartoons and a 2007 live action movie. He first appeared in his own cartoon on October 3rd, 1964 as a parody of Superman and other various superheroes. Wally Cox provided the rhyming voice for both Underdog and his secret identity, mild-mannered Shoeshine Boy.
On a weekly basis, villains such as Simon Bar Sinister, Cad and anthro wolf Riff Raff, The Electric (Slippery) Eel, Battyman, and Overcat would threaten the fair city and more importantly Underdog's girlfriend reporter Sweet Polly Purebred (a parody of Lois Lane). Mild-mannered shoeshine boy Shoeshine Boy would duck into a phone booth in a parody of Superman transformations and, in an explosion that would destroy the booth, become Underdog.
Underdog's powers originally come from a "Underdog Super Energy Vitamin Pill," but in the 80's and 90's, this was edited out from the cartoons as the producers didn't want to glorify drug use.
Although the series was canceled in 1973 and went into syndication, Underdog had entered cult status. He can be seen annually as a balloon at Macy's Thanksgiving Day Parade. He's also seen on t-shirts, commercials and parodied in cartoons.
On August 3rd, 2007, Walt Disney Pictures released a live-action Underdog motion picture, featuring the voice of Jason Lee as the voice of beagle Underdog. Amy Adams provided the voice of his sweetheart Polly Purebred. Actor Peter Dinklage played Underdog's archnemesis Simon Bar Sinister, while Alex Neuberger played Underdog's human friend. The movie was not based on any previous continuity of Underdog and offered a new, different perspective on the character and his origins.