Sam Rockwell was born on November 5, 1968, in San Mateo, California, to two actors, Pete Rockwell and Penny Hess. When he was two years old, his family moved to New York, where he spent his early childhood in the Bronx and Manhattan.
At the age of five, his parents separated, and he and his father moved to San Francisco. He spent summers and other times with his mother in New York.
Sam made his acting debut at the age of ten, alongside his mother, and later attended J Eugene McAteer High School in a program called SOTA. While still in high school, he appeared in the independent film Clownhouse (1989).
After graduating from high school, Sam returned to New York and had private training at the William Esper Acting Studio for two years. During this period, he appeared in various roles, including the ABC Afterschool Specials and HBO's Lifestories: Families in Crisis.
In 1994, a Miller Ice beer commercial enabled him to quit his day jobs and focus on his acting career. He went on to appear in five movies by 1996, including Basquiat, The Search for One-eye Jimmy, Glory Daze, Mercy, and Box of Moonlight.
Box of Moonlight was his breakout film, in which he played an eccentric character named the Kid. Although the film was not a commercial success, it received critical acclaim, and Sam's performance was praised.
In 1997, he starred in the critically acclaimed film Lawn Dogs, in which he played a working-class man living in a trailer. He also appeared in the quirky independent comedy Safe Men and the offbeat hitman trainee in Jerry and Tom.
After a few smaller appearances in films, Sam had larger roles in The Green Mile and Galaxy Quest, wowing audiences and critics with his chameleon-like performances.
More recently, he has appeared in mainstream films, including Charlie's Angels and The Hitchhiker's Guide to the Galaxy, while continuing to perform in smaller independent movies.
In 2018, he won an Academy Award for Best Supporting Actor for his role as a troubled police deputy in Three Billboards Outside Ebbing, Missouri (2017).