He is perhaps best known for his memorable performances in Pearport and Black Hawk Down, two major films that helped solidify his presence in Hollywood. In addition to those roles, he also appeared in a number of other notable projects such as The Virgin Suicides, 40 Days and 40 Nights, and the film adaptation of O. From 2014 to 2016, he took on a compelling role in the horror series Penny Dreadful, which further showcased his range as an actor.
Before he rose to fame, he started out like many aspiring actors—working at a local video store as his first job. His acting debut came in 1998 when he played the character Bill in the short film Debutante, marking the beginning of his journey in the entertainment industry.
Born to parents Wendy Anne and Daniel Hartnett, he grew up in a supportive family environment. In his personal life, he was in a high-profile relationship with actress Scarlett Johansson from 2005 to 2007, which drew considerable media attention.
On the family front, he and longtime partner Tamsin Egerton welcomed their first child in November 2015. The couple expanded their family with the arrival of their second child in August 2017, followed by a third in late 2019. After several years together and the shared experience of raising a family, he and Tamsin officially tied the knot in 2021, marking a new chapter in their lives.
He actually declined the opportunity to play Superman back in the early 2000s.