Colin Farrell says the idea of playing Alexander the Great—the Macedonian king who died at 32 after conquering much of the known world ca. 350 B.C.—was "completely irresistible." Yet his first meeting with director Oliver Stone three years ago was not promising. "I guess he was nervous," says Stone. "He had had a couple of pints that afternoon. It was kind of embarrassing because he dropped a few glasses. Seventy percent of what he said was in Gaelic. And he kept grabbing my knee, which I hate."

Though Stone wasn't impressed, Farrell, 28, pushed for another meeting. Because he had shaved his head to play a villain opposite Ben Affleck in 2003's Daredevil, Farrell put on a "Doris Day wig" and performed a reading from the script, recalls Stone. "It didn't look pretty. But he was amazing."

Though Alexander is not expected to be a blockbuster—reaction to early screenings has been mixed—playing the lead in the $150 million spectacle costarring Val Kilmer and Angelina Jolie is Farrell's biggest break yet, giving him global exposure. After capturing the attention of Hollywood in 2000's Tigerland, Farrell held his own with Al Pacino in The Recruit and Tom Cruise in Minority Report, but Alexander the Great may be the only role big enough to eclipse Farrell's epic carousing. The Dublin-born Farrell has made no secret of his enthusiasm for alcohol; his marriage to Quills actress Amelia Warner in 2001 lasted only four months; he and former girlfriend Kim Bordenave had a son last year; he's stepped out with Demi Moore and Britney Spears; and he has admitted to a staggering diet of drugs in his younger (even wilder) days.

During production of Alexander, he mooned the crowd in a Moroccan bar and generated headlines by spending last Christmas with Jolie. (They have since denied having a romance.) Just four days before filming wrapped in Thailand, Farrell fell down a flight of stairs after a night of partying, breaking his heel and wrist. "We wheeled him into battle and he got on a horse," says Stone. "He looked like a broken man, but he put out 100 percent."

And that is the secret to Farrell's success. Despite the offscreen antics, the actor remains an in-demand commodity in the film industry; he has several projects in the works, including, possibly, a big-screen version of Miami Vice for director Michael Mann. Says Jolie: "He knows when he needs to take care of business. I think that's why he should be allowed and excused to be as wild and crazy as he wants." She also notes that his wild-man image isn't entirely accurate: "I know about being typed with a wild image that doesn't always apply," she says. "So do Val [Kilmer] and Oliver. To have us all on one film made for tabloid heaven." Farrell says that he's as devoted to work as he is to play—"If I ever come in and [slur], that's bulls—t"—and indeed, he impressed his bosses on Alexander with his dedication. A devout smoker, Farrell says, "I get no kicks from the gym," but went through rigorous physical training in order to play the great warrior and whipped his body into impressive shape. Also, notes producer Moritz Borman, Farrell "talked to historians until their ears fell off."

Farrell is also growing into his role of father to son James, now 14 months old. Though Farrell and Bordenave have separate lives, James has visited his father on location; when he's not there, Farrell downloads pictures of his son from e-mail. "Something touched him when Colin became a father" last year, says a school friend. "His eyes go all gooey-gooey when he speaks about being a da. It's not the vodka talking." Fatherhood "is the best job I'll ever land," says Farrell, who still considers Dublin home and remains close to his family there. "He is very family-oriented," says pal Gavin Lambe-Murphy. "His mother, brother and sister work for him." When he visited Dublin in October, a group of mates all waited at a favorite pub expecting Farrell to show up. He never did, choosing instead to spend a quiet evening with his mum.

Of course, Farrell still maintains the ability to have a good time. Recently, when shooting director Terrence Malick's The New World in Williamsburg, Va., Farrell hit the bars, but the locals were impressed by how polite he was, never causing a ruckus and stepping outside to have a cigarette. One evening, while drinking with friends at the Fat Canary, he asked a waitress to drive him to his next stop. "The first thing Colin did was turn the radio all the way up," she recalls. Farrell—mostly sober but celebratory— "sang every word to every song," she says. "He was just a fun-loving guy, loves life, loves what he is doing."

Allison Adato. Carrie Bell, Mike Fleeman and Amy Longsdorf in Los Angeles, Declan White in Dublin, Pete Norman in London and Timothy Hogan in Williamsburg

  • Contributors:
  • Carrie Bell,
  • Mike Fleeman,
  • Amy Longsdorf,
  • Declan White,
  • Pete Norman,
  • Timothy Hogan.