In 1999, Sestero was cast as the lead in the horror movie Retro Puppet Master. Sestero's early acting work included minor roles in the television show Nash Bridges and the films Gattaca (1997) and Patch Adams (1998). His signing with Hollywood agent Iris Burton prompted his eventual move to Los Angeles. He returned to the United States to focus on acting, enrolling in the American Conservatory Theater in San Francisco. ĭuring his junior year of high school, Sestero began modeling, working in Milan and Paris for designers such as Giorgio Armani and Gianfranco Ferré. Sestero credits Hughes' gesture with inspiring him to pursue a professional acting career. He submitted the screenplay, along with a provisional poster, soundtrack suggestions and a request for a cross-promotional deal between 20th Century Fox and Walt Disney Pictures, to Hughes Entertainment, and eventually received a commendatory letter from John Hughes.

Sestero has said that he wrote a sequel to the then-recently released Home Alone at the age of 12, titled Home Alone 2: Lost in Disney World, which included a leading role for himself alongside Macaulay Culkin's Kevin McCallister. He was raised in Danville, California, where he attended Monte Vista High School. His mother is of French and Italian ( Sicilian) descent. Sestero was born in Walnut Creek, California.

He also appeared in a minor role as James, the Fiancé in the 2020 Netflix miniseries The Haunting of Bly Manor. Gregory Sestero (born July 15, 1978) is an American actor, filmmaker, model and author, best known for his role as Mark in the 2003 cult film The Room, as well as for his well-received memoir The Disaster Artist, detailing his experiences making The Room, which itself was later adapted into a 2017 film.

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