Joshua Daniel Hartnett (born July 21, 1978) is an American actor. He began his career on ABC's drama series Cracker (1997–1998), after which he became known as a teen idol through starring parts in films such as Halloween H20: 20 Years Later, The Faculty (both 1998), The Virgin Suicides (1999), Pearl Harbor, O, Black Hawk Down (all 2001), and 40 Days and 40 Nights (2002).
Hartnett continued to work steadily throughout the 2000s, with a mix of leading and supporting roles in Hollywood Homicide (2003), Wicker Park (2004), Sin City (2005), The Black Dahlia, Lucky Number Slevin (both 2006), 30 Days of Night (2007), August (2008), and I Come with the Rain (2009). He experienced a career resurgence with his roles as Ernest Lawrence in Oppenheimer (2023), a serial killer in Trap (2024), and a family husband in Verity (2026).
On television, Hartnett portrayed Ethan Chandler on the Showtime fantasy series Penny Dreadful (2014–2016). He also appeared in an episode of Black Mirror (2023) and guest-starred in The Bear (2024–2026).
Joshua Daniel Hartnett was born on July 21, 1978, in Saint Paul, Minnesota, the eldest child of Daniel Thomas Hartnett and Wendy Anne (née Kronstedt). He was raised by his father, a building manager and former guitarist for Al Green, and his stepmother, Molly, an artist. He has three younger siblings. Hartnett was raised Catholic, attending Nativity of Our Lord Catholic School. At Minneapolis South High School, he played football, but a knee injury forced him off the team when he was 16. He tried youth theater, acting in productions of The Adventures of Tom Sawyer and Guys and Dolls, and attracted attention from a talent scout. Originally interested in becoming a painter, he decided to pursue film acting while working in a video rental shop, where he became acquainted with films such as Trainspotting, 12 Monkeys, and The Usual Suspects.
After graduating from high school in 1996, Hartnett moved to Purchase, New York to attend the Conservatory of Theatre Arts & Film at the State University of New York at Purchase. He was expelled after writing a letter to the dean arguing that the college's evaluation system stifled students' creativity. At 19, he moved to Los Angeles at the recommendation of his manager, Nancy Kremer, who had previously helped him book television commercials.
Shortly after arriving in Los Angeles, he caught an improbable break, landing a part in the short-lived ABC drama Cracker. His first feature film was Halloween H20: 20 Years Later, in which he played the son of character Laurie Strode. Released on August 5, 1998, it performed well at the box office.
Hartnett developed a successful film career, appearing in The Faculty (1998), The Virgin Suicides (1999), and Black Hawk Down (2001). In 2001, he starred in the war drama Pearl Harbor. He was originally scheduled to play Tino in Deuces Wild but dropped out of the film. He also starred in O, an adaptation of William Shakespeare's Othello set in an American high school, playing Hugo, the film's version of Iago. In 2002, he starred in the romantic comedy 40 Days and 40 Nights.
In the early 2000s, Hartnett was approached several times to play the role of Clark Kent / Superman for a project originally helmed by Brett Ratner but always turned it down, not wanting to commit to a predicted ten-year role. Hartnett said, "It just wasn't the kind of movie I wanted to do. I turned down other superhero roles as well." For Christopher Nolan's Batman Begins, The Dark Knight, and The Dark Knight Rises, Hartnett declined the role of Bruce Wayne, which went to Christian Bale.
Hartnett was chosen as one of Teen People's "21 Hottest Stars Under 21" in 1999, Teen People's "25 Hottest Stars under 25", and one of People's "50 Most Beautiful People" in 2002. He was also voted Bliss magazine's "3rd Sexiest Male". During this period, he was marketed as a teen idol and a potential megastar; his unease with this public image led to his disillusionment with pursuing roles in high‑profile films.
Hartnett's next films included Hollywood Homicide (2003), Wicker Park (2004), Mozart and the Whale (2005), Sin City (2005), and Lucky Number Slevin (2006). He followed these roles with the 2006 drama-mystery The Black Dahlia, in which he played a detective investigating the real-life murder of waitress Elizabeth Short. Hartnett had been cast five years earlier and remained committed to the film because he liked the subject matter.
His 2007 roles included Resurrecting the Champ and the graphic novel-based 30 Days of Night, in which he played a small-town sheriff. Hartnett described the second film as "supernatural, but kind of a western". He was going to play trumpet player Chet Baker in The Prince of Cool but left the project after disagreeing with the producer's ideas.
In 2008, Hartnett played Charlie Babbit in the stage adaptation of Barry Morrow's film Rain Man at the Apollo Theatre in London's West End. He starred in the Emporio Armani fragrance campaign, "Diamonds for Men", becoming the first male celebrity to represent Giorgio Armani Beauty. He has appeared on magazine covers including Cosmogirl, Details, Entertainment Weekly, Girlfriend, Seventeen, Vanity Fair, GQ, and Vman, and in magazines such as Vogue, Elle, People, Glamour, In Touch, and InStyle.
In 2009, Hartnett produced the music video for Kid Cudi's "Pursuit of Happiness". During this period, he acted in several direct-to-DVD and international films that received negative reviews, including August (2008), I Come with the Rain (2009), Bunraku (2010), Girl Walks into a Bar (2011), Stuck Between Stations (2011), The Lovers (2013), Parts per Billion (2014), and Wild Horses (2015). In 2013, he was a guest of honor on Off Plus Camera.
In 2014, he was cast as Ethan Chandler in the Gothic horror series Penny Dreadful, which was filmed in Dublin and other locations in Ireland. His character was later revealed to be Lawrence Talbot / the Wolfman. In 2017, he performed in Atsuko Hirayanagi's independent film Oh Lucy!, which premiered at the Cannes Film Festival. That year, he also starred in and produced the survival film 6 Below: Miracle on the Mountain, which received negative reviews. He continued acting in smaller films that were received negatively, including The Ottoman Lieutenant (2017), She's Missing (2019), Inherit the Viper (2019), Valley of the Gods (2019), and Ida Red (2021).
In 2020, he portrayed Canadian journalist Victor Malarek in the crime drama Target Number One. Hartnett appeared in Guy Ritchie's Wrath of Man (2021) in a supporting role before Ritchie cast him in Operation Fortune: Ruse de Guerre (2023). In January 2022, Hartnett was cast as Ernest Lawrence in Nolan's Oppenheimer (2023). In July 2022, he joined the sixth season of Black Mirror.
In 2024, he starred in M. Night Shyamalan's thriller Trap, playing Cooper Abbott, a serial killer, known as "the Butcher". Between 2024 and 2025, Hartnett played Frank in the third season of The Bear. In December 2024, he joined the cast of Verity, the film adaptation of Colleen Hoover's 2018 novel.
In 2025, Hartnett starred in the action film Fight or Flight, playing a mercenary tracking a target on a plane.
Hartnett began a relationship with English actress Tamsin Egerton in 2012. They have four children. The couple married in November 2021. They live in Hampshire, England.