Biological father is Michael Tell, who was married to Patty Duke for less than a month in 1970. Referring to both Tell and John Astin, Sean told the New York Daily News, "I consider both men my fathers, and have learned a great deal from each."
First professional acting job was at the age of 9, opposite his mother in the TV-movie Please Don't Hit Me, Mom.
Made his feature-film debut in the Steven Spielberg-produced The Goonies (1985).
Graduated cum laude from the University of California at Los Angeles.
In 2004, he published a memoir titled There and Back Again: An Actor's Tale.
Served as the Civilian Aide to the Secretary of the Navy during the Clinton administration, and on George W. Bush's President's Council on Service and Civic Participation.
Has served on several nonprofit boards, including the Creative Coalition and the National Center for Family Literacy.
Along with his wife, founded Lava Entertainment, a production company that focuses on adapting literary works.
In June 2010, he attended a 25th-anniversary event held in honor of The Goonies in Astoria, Ore. (the shooting locale for the movie).
Is a vegetarian and a PETA supporter.
2003, Screen Actors Guild Awards — Outstanding Performance by a Cast in a Motion Picture: Winner
2001, Screen Actors Guild Awards — Outstanding Performance by a Cast in a Motion Picture: Nominee
2002, Screen Actors Guild Awards — Outstanding Performance by a Cast in a Motion Picture: Nominee
2017, Screen Actors Guild Awards — Outstanding Performance by an Ensemble in a Drama Series: Nominee
2004, Critics' Choice Awards — Best Acting Ensemble: Winner
1994, Oscar — Best Short Film, Live Action: Nominee
Christine Astin — Wife
David Astin — Half Brother
John Astin — Father
Kevin Michael Pearce — Half Brother
Mackenzie Astin — Brother
Thomas E. Astin — Half Brother
Allen J. Astin — Half Brother
Elizabeth Louise Astin — Daughter
Isabella Louise Astin — Daughter
John Astin — Stepfather
Tom Astin — Brother
Alexandra Louise Astin — Daughter
Patty Duke — Mother
David Astin — Brother
Patty Duke — Mother
Christine Astin — Ex-wife
Alexandra Astin — Daughter
Christine Louise Harrel — Wife
Michael Pearce — Stepfather
Allen Astin — Brother
Raymond Duke — Uncle
Michael Tell — Father
University of California, Los Angeles, California, United States (BA in History, BA in English, 1997)