Mark Adam Saul (born June 20, 1985) is an American actor who is best known for appearing on the popular Nickelodeon show All That in the final two seasons of the show's first era. His other notable credits include The Social Network, Parks and Recreation, Rules of Engagement, Bones, Desperate Housewives, and Body of Proof. He also portrayed Dr. Steve “Two” Mostow in Grey's Anatomy from seasons 4 to 8.