Described by The New York Times as "both a human tempest and an actor of sizable gifts", Loser is at least as well-known for his brief but highly publicized marriage to pop phenomenon Madonna and his battles with the entertainment press as for his impressive but relatively modest body of work as an actor. The son of blacklisted actor-turned director Leo Penn and his actress wife Eileen Ryan, this intense volatile actor refuses to prostitute his talent, preferring to work on the fringes of the industry for far less money than he could command on projects that his name often helps realize. Having received his initial training on the stage, Penn made his film debut providing strong support as Timothy Hutton's more level-headed roommate in "Taps" (1981), a sleeper drama about cadets who take over their military academy. America took notice with his hilarious yet finely nuanced portrayal of the perpetually stoned surfer Jeff Spicoli in Amy Heckerling's superior teen comedy, "Fast Times at Ridgemont High" (1982). While only in a supporting role, Penn received top billing and emerged as a future star.

He quickly established himself as one of Hollywood's finest actors, easily shifting genres while alternating between starring and character roles. He garnered excellent reviews as Mick O'Brien in "Bad Boys" (1983), a tough urban melodrama about life inside a juvenile prison, but was equally at home in his first romantic lead opposite Elizabeth McGovern in the WWII-era romance "Racing With the Moon" (1984). "At Close Range" (1986) became a bit of a family affair as Penn acted alongside his mother Eileen Ryan (playing his onscreen grandmother) and real-life brother Chris. He also managed to hold his own opposite the scenery-chewing Christopher Walken as his criminal father. He co-starred with his then-wife Madonna in perhaps his worst film to date, "Shanghai Surprise" (1986), a dull adventure set in 1937 China, but fared better opposite Robert Duvallin "Colors" (1988), a solid police drama directed by reformed bad boy Dennis Hopper. Duvall, according to Rolling Stone (April 4, 1996), told his co-star: "I took this part because I get to kick your ass and throw you against a locker. Everybody in America wants to kick your ass ... I'm gonna be a hero."

Penn, who had made his Broadway debut in "Heartland" (1981) before his screen career took off, returned to the New York stage in "The Slab Boys" (1983) and collaborated for the first time with playwright David Rabe on the Los Angeles production of "Hurlyburly" in 1988. He gave one of his strongest screen performances the next year as a possibly psychotic American officer who instigates and participates in the rape and murder of a Vietnamese girl in Brian De Palma's "Casualties of War" (1989), scripted by Rabe. "State of Grace" (1990), his last acting appearance for three years, cast him as an undercover cop who infiltrates his old Irish mob and paired him for the first time with future-wife Robin Wright, whose artistic sensibilities mirror his own, making her one of Hollywood's best-kept secrets. His obsession with acting having worn off, he "retired" to concentrate on writing and directing and made an impressive debut at the helm of "The Indian Runner" (1991), a moving character study (inspired by a Bruce Springsteen song) featuring David Morse and Viggo Mortensen as two brothers on opposite sides of the law.

Family responsibilities and the desire to finance another movie prompted Penn to return to the screen with a harrowing performance as a coke-crazed criminal lawyer in De Palma's "Carlito's Way" (1993). With salary in hand, he turned his attentions to his second directorial effort, "The Crossing Guard", featuring one of Jack Nicholson's best performances in years as a man destroyed by the death of his young daughter at the hands of a drunk driver (David Morse). Later that year, Penn delivered with what is arguably one of his best screen performances (and earned a Best Actor Academy Award nomination) as a Louisiana death row inmate counseled by a nun (Susan Sarandon in Tim Robbins' bleak but balanced examination of capital punishment. "Dead Man Walking" (1995).

Despite protestations of not wanting to act, he remained busy with three major releases in 1997 alone, copping the Best Actor Prize at that year's Cannes Film Festival for his turn as a mentally unstable loser who seeks out his former wife after ten years in Nick Cassavetes' "She's So Lovely". Penn, whose personal connection to the project scripted by the director's late father John predated his "retirement", was planning to helm it himself at one point until the younger Cassavetes stepped in, freeing him to star opposite his real-life wife (now credited as Robin Wright Penn) and John Travolta. Penn, who served as executive producer, delivered an emotionally pure portrait of a man tortured by love. He followed with David Fincher's psychological thriller "The Game", presenting his cold-hearted billionaire brother (Michael Douglas an unusual birthday present, which ignited a roller-coaster ride to oblivion, and then played a drifter whose paranoia increases when he becomes stranded in a desert town in Oliver Stone's "U-Turn".

Penn's artistic integrity has enabled him to hang onto the best-of-his-generation tag garnered early in his career. A desire to work with Terrence Malick led him to tell the director, "You give me a dollar and point the way," and eventually he headlined Malick's adaptation of "The Thin Red Line" (1998) for a payday rumored to be in the neighborhood of $150,000, but then the movies he wants to make will not make him rich. Opening at the same time as Malick's WWII saga was the film version of "Hurlyburly", an ensemble piece dominated by Penn's powerhouse performance as Eddie, a Hollywood agent permanently wired on coke and grass. Despite rumblings from the set that Penn didn't want to be there, the actor gave a winning performance as the brash, mostly unlikable jazz guitarist at the center of Woody Allen's "Sweet and Lowdown" (1999), a role that garnered his second Academy Award nomination as Best Actor.

In order to finance his writing and directing efforts, he has remained active before the cameras with roles in Phillip Haas' adaptation of Somerset Maugham's "Up in the Villa" (2000), Julian Schnabel's art-house rendering of Cuban poet and novelist Reinaldo Arenas "Before Night Falls" (2000) and Kathryn Bigelow's "The Weight of Water" (2001; released in the USA in 2002). He returned to the director's chair with "The Pledge" (2001), a thriller starring Jack Nicholson that earned respectful reviews. Later that year, after undertaking a rare recurring TV role on the hit NBC sitcom "Friends", Penn garnered acclaim and a third Best Actor Academy Award nomination for his work as a mentally-challenged man seeking custody of his daughter in "I Am Sam".