Greg Sestero is an American actor, producer, and author, best known for his role as Mark in the cult film The Room. Released in 2003, the film gained notoriety for its unconventional storytelling and production quality, leading to a dedicated fanbase. In addition to acting, Sestero co-wrote the memoir The Disaster Artist with Tom Bissell, which details the making of The Room and its impact on popular culture. The book was later adapted into a film directed by James Franco, further solidifying Sestero's connection to the unique legacy of The Room.