Clark Gregg has spun a successful career on the New York stage into a growing profile in motion pictures and television as an actor, writer, and director. Clark Gregg's career as an actor began when he was a student at New York University, where he became a protégé of noted playwright and director David Mamet. Mamet cast Gregg in his first film role -- a small part in 1988's Things Change -- and that same year he made his off-Broadway debut in Howard Korder's play A Boy's Life. With Mamet's help, Gregg co-founded the esteemed Atlantic Theater Company in New York in the late '80s, and in 1990, Gregg made his Broadway debut in Aaron Sorkin's drama A Few Good Men. Through the 1990s, Gregg gave a number of strong supporting performances in such films as Clear and Present Danger, The Usual Suspects, and Magnolia, with Gregg earning a Best Supporting Actor nomination at the Independent Spirit Awards for his striking turn as a transsexual in the independent feature The Adventures of Sebastian Cole. In television, Gregg scored recurring roles on the shows The Commish and Sports Night, as well as guest appearances on Sex and the City and The West Wing. And he remained a near-constant presence on the New York stage, earning Outer Critics Circle, Obie, and Drama Desk nominations for his work. Gregg also began directing for the stage, including well-received productions of Mamet's Edmond and Kevin Heelan's Distant Fires. In the late '90s, Gregg developed an interest in screenwriting, and began working on a supernatural thriller in his spare time. As chance would have it, Gregg's script came to the attention of Robert Zemeckis, who was eager to direct a thriller; Gregg's first screenplay became What Lies Beneath, which starred Michelle Pfeiffer and Harrison Ford, and became a major box-office success. Gregg moved on to directing for the big screen with his next screenplay, the independent drama Natural Selection.