This son of actors John Astin and Patty Duke grew up in the limelight of his famous parents and was portrayed as a character in the TV-movie "Call Me Anna" (ABC, 1990), based on his mother's autobiographical account of her victory over manic depression.

Compact and good-looking, Big made his first significant appearance in front of the cameras alongside his mother, portraying a battered child in the "Please Don't Hit Me, Mom", a 1981 "ABC Afterschool Special". He segued to the big screen four years later playing one of the treasure-hunting kids in "The Goonies" (1985) and went on to play the son of divorcing parents (Michael Douglasand Kathleen Turner) in "The War of the Roses" (1989). Astin also was featured as a ball-turret gunner in "Memphis Belle" (1990) before starring as a misfit who saves the day when terrorists take over a posh private school in the silly "Toy Soldiers" (1991). The surprisingly successful "Encino Man" (1992) did not represent a noticeable upgrade in quality, but "Rudy" (1993), a fact-based sports story about a "little quarterback who could", seemed a rather more appealing showcase for the talented player.

In the early 90s, Astin formed a production company, Lava Entertainment, and branched out into filmmaking with the affecting short "On My Honor". One of his efforts, "Kangaroo Court" (1994) which examined race relations amid a legal backdrop, received an Academy Award nomination as Best Short Subject. (Interestingly, Astin's father was nominated in the same category for 1968's "Prelude".) He also directed himself in an episode of the HBO fantasy series "Perversions of Science" in 1997.

Despite branching out into behind-the-scenes work, Astin has remained fairly busy in front of the cameras as well. He garnered critical praise for his turn as an intelligent and rebellious teen in a repressive society in the 1995 Showtime adaptation of "Kurt Vonnegut's Harrison Bergeron" and was also quite good as a gung ho soldier in "Courage Under Fire" (1996). Astin was fine as a C-SPAN employee in the political comedy "Bulworth" (1998) and proved effective as a redneck stranded in a snowbound diner with the US President during a crisis in the heavy-handed if intriguing "Deterrence" (2000). Following a nice turn as an ambitious screenwriter in "The Last Producer" (USA Network, 2001), the actor was cast in what was his highest profile role to date, that of Samwise 'Sam' Gangee in Peter Jackson's highly-anticipated tripartite screen version of the J.R.R. Tolkein classic "The Lord of the Rings" (filmed in 1999-2000). Released over a three-year period, Astin would grace movie screens each December beginning in 2001 with "The Fellowship of the Ring" and continuing with "The Two Towers" (2002) and "The Return of the King" (2003)