Is the second actor from a "Lord of the Rings" adaptation to have a relative in an Addams Family adaptation. His father, John Astin, played Gomez on "The Addams Family" (1964). John Huston, who voiced Gandalf in the animated version of The Return of the King (1980) (TV), is the father of Anjelica Huston, who played Morticia in the films.
Keith Coogan is the grandson of Jackie Coogan who played Uncle Fester in "The Addams Family" (1964). Sean Astin is the son of John Astin who played Gomez Addams in "The Addams Family" (1964). Keith Coogan and Sean Astin played friends in Toy Soldiers (1991).
His biological father is actually Michael Tell, whom Patty Duke was married to for less than a month in 1970. Sean was adopted at age 3 by John Astin, but considers both men to be his father.
Started his own production company, Lava Entertainment, in the late 1980s.
Left the room halfway during recording DVD commentary for The Goonies (1985) and never returned. The recording session started late, and Sean had an earlier commitment to introduce friend Joe Pantoliano who was M.C.'ing at a local theatre. Left the recording studio to change clothes, then returned to explain why he had to leave, give a "shout out to Joey Pants," and left an action figure of Sam Gamgee to take his place. However, the departure and explanation were edited out by the DVD producers.
In The Goonies (1985), his character cries out "Holy Mackenzie!" His brother is Mackenzie Astin. He claimed he was allowed to keep the treasure map used in the film. However, the map was lost forever when his mother discovered it several years later, thought it was just a crinkled piece of paper, and threw it in the trash.
Believed that Desi Arnaz Jr. was his biological father until a blood test in 1990 revealed that Michael Tell is his biological father.
Daughter born: Alexandra Astin. [27 November 1996]
On 4 December 2001, Sean had his image as Samwise Gamgee immortalized on a 90-cent New Zealand postage stamp that he shares with "Lord of the Rings" co-star Elijah Wood (Frodo Baggins). However, Sean's last name is spelled incorrectly on the presentation pack of the stamps (Austin instead of Astin).
While filming The Lord of the Rings: The Fellowship of the Ring (2001), Astin (as Samwise Gamgee) ran into a lake to stop Frodo (Elijah Wood). When he did this, he stepped on a piece of glass and had to be rushed to the hospital. He received many stitches to repair the injury.
Has hit bad guys over the head with a frying pan in two different movies: as Sam Gamgee in The Lord of the Rings: The Fellowship of the Ring (2001) and also as Billy Tepper in Toy Soldiers (1991).
August 6, 2002, welcomed second child daughter Elizabeth Louise.
In February 2003, Sean was appointed to the President's Council on Service and Civic Participation.
Announced at the Texas Film Festival on 22 February 2003 that he has optioned the book "Issac's Storm" and is planning on shooting an epic film centered around the Galveston Hurricane of 1900.
Appeared at Wizard World signing autographs on August 9, 2003.
He and his father, John Astin, have both appeared in a Best Picture winner. Sean appeared in The Lord of the Rings: The Return of the King (2003) and John appeared in West Side Story (1961).
September 2004 - Attended the Armaggeddon Pulp Culture Expo Convention in Wellington, New Zealand, as a Lord of the Rings guest.
Wanted to direct Fantastic Four (2005) at one point.
July 22, 2005, welcomed third child, daughter Isabella Louise at 5lb 4oz. She was a month premature
Gave the 2008 commencement address at Luther College, Decorah, Iowa, along with Kent Stock, Luther alum, whose story Sean depicted in The Final Season (2007).