Dunn was cast as a series regular for the first season of Veronica Mars as Duncan Kane, but left halfway through season 2 in the episode "Donut Run." He came back for a cameo in the season finale of season 2, "Not Pictured," but did not reprise his role in the third season. He also appeared in the 2004 remake of The Manchurian Candidate. The same year, he had a guest appearance on Gilmore Girls. He also had a guest appearance on Grey's Anatomy in 2006. He appeared in the 2008 film Jumper as Mark Kobold.