Starr co-starred in the 2007 comedy film "Knocked Up", which was directed by Judd Apatow. The same year, he had small appearances in "Superbad" and "", both of which were produced by Apatow. "Knocked Up" was critically praised and was a smash at the box office. The success of "Knocked Up" led to Starr having larger roles in films, such as "Good Dick" and "Adventureland". Starr also appears in many well-received short films that premiere at film festivals, such as the Sundance Film Festival.