One of the crop of obscenely attractive young stars to pop up during the late 1990s, Josh Hartnett has the kind of strong-jawed, puppy-eyed looks that make him equally suited for both movie stardom and Tommy Hilfiger ads.

Hartnett was born in St. Paul, Minnesota, on July 21, 1978. Following his high school graduation, he attended New York's SUNY-Purchase, but his time there ended after he was offered a role on the short-lived TV series Cracker. He also did a number of TV commercials and plays, and in 1998 he got his screen break with the plum role of Jamie Lee Curtis' son in Halloween: H20. Although the film received poor reviews, it did moderately well at the box office, and that same year Hartnett's profile further increased when he starred in The Faculty. One of a number of films to exploit the current trend in teen horror movies, it featured Hartnett fighting off alien teachers alongside the likes of fellow up-and-comers Elijah Wood and Shawn Hatosy. Although the film didn't do as well as expected, thanks in part to the fact that the teen horror craze was beginning to lose steam, it in no way interfered with the increasing number of opportunities available to the young actor.

Hartnett could subsequently be seen in a number of diverse films; among his projects in 2000 alone, he played an Iago-like character in O, the teen re-telling of Othello; the son of Warren Beatty and Diane Keaton in the comedy-drama Town and Country; and the paramour of the eldest of the ill-fated Lisbon sisters in Sofia Coppola's adaptation of The Virgin Suicides. His pattern of starring in films with steadily-increasing budgets reached its apex in 2001 when Hartnett appeared in director Michael Bay's World War II action drama Pearl Harbor, playing Danny, a young soldier who falls in love with his best friend's main squeeze amid the chaos of the titular conflict. Later that same year Hartnett would fight a whole new war in Ridley Scott's Oscar-winning war drama Black Hawk Down, and shortly after swearing off sex for 40 Days and 40 Nights and hitting the street beat with Harrison Ford in the coolly-received buddy cop comedy Hollywood Homicide, the handsome heartthrob would make public his desire to shift his attentions away from blockbuster territory in order to focus his talents on smaller films of increased quality - even if it did mean a leaner paycheck. Though subsequent rumors of his potential involvement with the long-in-development Superman film would seem to betray this sentiment, lower-profile roles in such independent-minded efforts as Sin City and Mozart and the Whale ultimately served to underscore the maturing actor's sincerity. Of course Hartnett wasn't averse to appearing in the occasional mainstream effort, with roles in Wicker Park and Lucky Number Sleven serving to occupy a curious cinematic middle ground between the indie and blockbuster mindsets.

By the time Hartnett took a prominent role in Brian De Palma's 2006 true crime drama The Black Dahlia, it appeared as if the actor's willingness to challenge himself onscreen had finally begun to pay off. A dark look at the Hollywood underbelly based on author James Ellroy's best-selling novel, The Black Dahlia preceded an introspective turn as an emerging sports writer who befriends a former boxing champ many had thought dead in Resurrecting the Champ, and a highly challenging role as legendary jazz trumpeter Chet Baker in director Bruce Beresford's The Prince of Cool. Hartnett plays a former police officer who agrees to investigate the disappearance of the son of a wealthy businessman in I Come With Rain (2008), and joined the cast of the highly stylized fantasy drama Bunraku (2010). The actor played a supporting role in the critically acclaimed independent drama Stuck Between Stations in 2011.

In 2014, Hartnett returned to his TV roots in the horror drama series Penny Dreadful.