Born Henry Jackson Thomas, Jr. in San Antonio, TX to parents Hazel and Henry Jackson, Sr., Thomas knew he wanted to act from the age of five. At age eight, he persuaded his mother to take him to his first casting call. This eventually led to his debut at the age of 10 in the period drama "Raggedy Man" (1981), as the son of Sissy Spacek, a single mother plagued by gossip in a small town during World War II. Thomas also made his television bow that year in "The Steeler and the Pittsburgh Kid" (NBC, 1981), an inspirational family drama based on a popular Coke commercial at the time. However, no one could have ever predicted the success or cultural impact of his sophomore film effort, director Steven Spielberg's family-friendly, sci-fi blockbuster "E.T. The Extra-Terrestrial" (1982). As Elliot, the gentle boy who discovers a stranded alien in his suburban backyard, Thomas delivered an utterly heartfelt performance, devoid of the shameless mugging so often encouraged by directors working with child actors. Along with his fellow child co-star, Drew Barrymore, he soon found his youthful talents in high demand with Hollywood casting directors. His first project post-"E.T." was "Misunderstood" (1984), a powerful drama about the reconciliation between a newly widowed father (Gene Hackman) and his estranged young son (Thomas). His follow-up, "Cloak and Dagger" (1984), a Hitchcockian thriller for the juvenile set conveniently shot in San Antonio, would be his last Hollywood feature film for nearly a decade. Thomas starred in one more film, the likable Australian childhood adventure "The Quest" (1986), before taking time off from acting to grow up and strategize his future.After graduating from East Central High School and briefly attending nearby Blinn College for a year, Thomas returned to the screen in "Murder One" (1988), a Canadian feature about three young prison escapees who go on a murderous crime spree after stealing a car. He proved capable in period fare as an amorous young music teacher in acclaimed director Milos Forman's "Valmont" (1989), an adaptation of the 18th-century French novel, Les Liaisons Dangereuses. With a flair for playing lonely, introverted youths, Thomas was an apt, albeit unexpected, choice to play the young Norman Bates in "Psycho IV: The Beginning" (Showtime, 1990), a quasi-sequel/prequel to the original Hitchcock masterpiece. He made his return to U.S. features with a supporting role in the cult-classic UFO drama, "Fire in the Sky" (1993), as the friend of a man (D.B. Sweeney) who claimed to have been abducted by aliens. He had a more sizable role in the epic period drama "Legends of the Fall" (1994), as the idealistic younger brother of Aidan Quinn and Brad Pitt whose mettle is tested on the battlefields of WWI and whose death sets in motion a series of tragic events. Thomas followed with a series of made-for-TV movies, including an adaptation of playwright Sam Shepard's "Curse of the Starving Class" (Showtime, 1995), as well as a docudrama about an infamous child molestation witch hunt, "Indictment: The McMartin Trial" (HBO, 1995), and "Riders of the Purple Sage" (TNT, 1996), the fifth adaptation of Zane Grey's classic Western novel.In the comedy "Hijacking Hollywood" (1996), Thomas played an aspiring filmmaker who steals footage from a special effects-laden sequel to the book Moby Dick in an effort to finance his own movie project. He made impressive turns in such indie features as the idiosyncratic romantic drama "Niagara, Niagara" (1997) and "Suicide Kings" (1997), a quirky crime comedy starring Christopher Walken as a kidnapped mob boss. Two years after starring in "Hijacking Hollywood," Thomas experience a bit of celluloid six-degrees of separation when he starred as young Ishmael in the big-budget miniseries "Moby Dick" (USA, 1998), a more traditional take on Melville's tale of nautical obsession, starring Patrick Stewart as Capt. Ahab. He rode south of the border with Matt Damon in "All the Pretty Horses" (2000), director Billy Bob Thornton's cinematic interpretation of Cormac McCarthy's revered neo-Western novel. In a lower-profile project, Thomas co-starred in the thriller "Dead in the Water" (2002), a lackluster remake of director Roman Polanski's 1962 tale of fear and self-destruction, "Knife in the Water." Far better received was revered director Martin Scorese's bloody period drama "Gangs of New York" (2002), in which the young actor landed a supporting role alongside stars Leonardo DiCaprio and Daniel Day-Lewis.Thomas played a drunk driver at the heart of several interconnected stories in "11:14" (2003), a black comedy co-starring Hilary Swank. He followed with a series of macabre television projects, beginning with a 2005 Mick Garris-directed episode of the anthology series "Masters of Horror" (Showtime, 2005-07), and reteamed with Garris for the adaptation of Stephen King's novel of terror in a desolate southwestern town in "Desperation" (ABC, 2006). Thomas stayed in the world of horror with "The End of the Whole Mess," an episode from the miniseries "Nightmares & Dreamscapes: From the Stories of Stephen King" (TNT, 2006), in which he played a man whose desire for world peace brings about unexpected consequences. In 2008, he also picked up work as a returning character in two episodes of the procedural drama series "Without a Trace" (CBS, 2002-09). Thomas next played a skeptical producer whose director is being haunted by the spirit of an actress that died in the same decrepit film studio decades earlier in the shocker "Don't Look Up" (2009). In "Dear John" (2010), he portrayed the husband of a young woman (Amanda Seyfried) harboring an unrequited love for a soldier (Channing Tatum) with whom she had corresponded for years.