Sean Astin (born on February 25, 1971) is an American film actor, director, and Academy Award-nominated producer best known for his film roles as Mikey Walsh in The Goonies, the title character of Rudy, and Samwise Gamgee in the Lord of the Rings trilogy. In television, he guest starred as Lynn McGill on the fifth season of 24.

Astin was born Sean Patrick Duke in Santa Monica, California, the son of actress Patty Duke. He discovered in 1994 that his biological father is Michael Tell, a music promoter and writer who edits and publishes the Jewish newspaper The Las Vegas Israelite. Tell's marriage to Patty Duke was annulled shortly before her marriage to John Astin. At the time of his birth, it was widely assumed that his biological father was Desi Arnaz, Jr., although this was later proven false. Astin is the older half-brother of Mackenzie Astin, also an actor (in The Facts of Life).

Astin graduated from UCLA with a B.A. in History and English (American literature and culture). He is an alumnus of and now serves on the Board of Directors of the Patrons Association and the Arts Council for Los Angeles Valley College. He attended St. Paul the Apostle Elementary School, Bellagio Road Elementary, and the Crossroads High School for the Arts and participated in master classes at the Stella Adler Conservatory in Los Angeles.