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 the episode of Black Mirror (2023) and guest-starred in The Bear (2024–2026).
Hartnett was born in Saint Paul, Minnesota. The son 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 named Jake, Joe, and Jessica. 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 went on to try youth theater, where he acted 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 become a film actor 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 contending that the college's evaluation system stifled students' creativity. At the age of 19, Hartnett 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 drama series Cracker on ABC. 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 major films 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 the role of Tino in Deuces Wild, but dropped out from the film. He also starred in O, an adaptation of William Shakespeare's Othello set in an American high school, as Hugo, the film's version of Iago. In 2002, he starred in the romantic comedy film 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 of his decision, "It just wasn't the kind of movie I wanted to do. I turned down other superhero roles as well." For Christopher Nolan's trilogy of films 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", both 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 the public image eventually 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 up these roles with the 2006 drama-mystery The Black Dahlia, in which he played a detective investigating the notorious real-life murder of waitress Elizabeth Short. Hartnett had been cast in the role five years before the film was produced, remaining committed to appear in the film because he liked the subject matter.
Among his 2007 roles were 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 film The Prince of Cool but did not agree with the producer's ideas and left the project.
In 2008, Hartnett played Charlie Babbit in the theater adaptation of Barry Morrow's Academy Award-winning film Rain Man at the Apollo Theatre in London's West End. He starred in the new campaign of the Emporio Armani fragrance, "Diamonds for Men", being featured in both print and TV ads for the fragrance, thus becoming the first male celebrity to represent Giorgio Armani Beauty. He has been featured on many magazine covers, such as Cosmogirl, Details, Entertainment Weekly, Girlfriend, Seventeen, Vanity Fair, GQ and Vman, in addition to being in other magazines like Vogue, Elle, People, Glamour, In Touch, and InStyle.
In 2009, Hartnett produced the music video for the rapper Kid Cudi's song "Pursuit of Happiness". During this time, Hartnett acted in several direct-to-DVD films and international films which received negative reviews, such as the drama August (2008), the thriller I Come with the Rain (2009), the martial arts action film Bunraku (2010), the comedy film Girl Walks into a Bar (2011), the romantic comedy Stuck Between Stations (2011), the time travel adventure film The Lovers (2013), the romantic drama Parts per Billion (2014), and Wild Horses (2015). In 2013, Hartnett was a guest of honor on Off Plus Camera.
In 2014, he was cast in the part of Ethan Chandler in the Gothic horror series Penny Dreadful, which was shot in locations around Dublin and Ireland. Later, Hartnett's character was revealed to be Lawrence Talbot / the Wolfman, who had changed his name to distance himself from his family. In 2017, he performed in Atsuko Hirayanagi's critically acclaimed independent film Oh Lucy! (2017), which premiered at the Cannes Film Festival. That same year, he starred in and produced the survival film 6 Below: Miracle on the Mountain, which received negative reviews. He then continued acting in smaller films which were received negatively, such as the Turkish war film The Ottoman Lieutenant (2017), the drama She's Missing (2019), the crime film Inherit the Viper (2019), the Polish film Valley of the Gods (2019), and the crime film Ida Red (2021).
In 2020, he portrayed Canadian journalist Victor Malarek in the crime drama Target Number One. Hartnett starred in Guy Ritchie's 2021 revenge drama film Wrath of Man in a supporting role before Ritchie cast him in his 2023 film Operation Fortune: Ruse de Guerre. In January 2022, Hartnett was cast as Ernest Lawrence in Nolan's biographical film Oppenheimer. In July 2022, he joined the sixth season of Black Mirror.
In 2024, he starred in M. Night Shyamalan's thriller film Trap where he played 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, Hartnett joined the cast for the 2026 film adaptation of Colleen Hoover's novel Verity, alongside Anne Hathaway and Dakota Johnson.
In 2025, Hartnett starred in the action film Fight or Flight, playing a mercenary tracking a target on a plane.
Hartnett has been involved in various causes. In 2007, he took time out from filming to support the green lifestyle campaign of Global Cool.