Dewey Cox is a fictional character from the musical comedy film "Walk Hard: The Dewey Cox Story," released in 2007. The film parodies the biographical musical genre, particularly the life stories of famous musicians like Johnny Cash and Elvis Presley. Dewey is portrayed as a talented but troubled singer-songwriter who navigates the ups and downs of fame, love, and personal struggles. The character is played by John C. Reilly, who also performs the film's original songs. "Walk Hard" humorously explores themes of addiction, relationships, and the music industry, while showcasing Dewey's journey from obscurity to stardom.