Sullivan was born in Los Angeles, California. He played the role of Dabney Hooper on "Malcolm in the Middle" from 2000 to 2003. Sullivan is also the voice actor for Danny O'Farrell and Everitt Konquist on the Disney animated series "Fillmore!" . He was a guest on television programs such as "The Secret World of Alex Mack", "Seinfeld", "The Amanda Show", "NewsRadio", "Chicago Hope", "Mad About You", "ER", "Scrubs", and "Max Keeble's Big Move".