- 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.
- 1994, Oscar — Best Short Film, Live Action: Nominee
- 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
- 2004, Critics' Choice Awards — Best Acting Ensemble: Winner
- Christine Astin — Wife
- David Astin — Half Brother
- Michael Pearce — Stepfather
- Michael Tell — Father
- Alexandra Louise Astin — Daughter
- Isabella Louise Astin — Daughter
- Patty Duke — Mother
- Mackenzie Astin — Brother
- Thomas E. Astin — Half Brother
- John Astin — Father
- Allen J. Astin — Half Brother
- Elizabeth Louise Astin — Daughter
- Kevin Michael Pearce — Half Brother
- Raymond Duke — Uncle
- University of California, Los Angeles, California, United States (BA in History, BA in English, 1997)
Season 4, Episode 9
- Birth Name: Sean Patrick Astin
- Birth Place: Santa Monica, California, United States
- Birthday: February 25, 1971, Pisces
- Profession: Actor, Director, Producer