1. He first came to attention in 1997 for his role as Michael Fitzgerald in the television crime drama series Cracker.
2. He made his feature film debut in 1998 in the slasher film Halloween H20: 20 Years Later, followed by teen roles in films such as the sci-fi horror film The Faculty .
3. Hartnett had starring roles in the war film Pearl Harbor, the drama O, the war film Black Hawk Down, the romantic comedy 40 Days and 40 Nights, and the mafia thriller Lucky Number Slevin.
4. Il a joué dans le thriller néo-noir Brian De Palma dirigée Le Dahlia Noir qui fut un échec commercial et critique.
5. He stars as Ethan Chandler in the horror TV series Penny Dreadful.
6. After finishing high school, a move to New York to attend the Conservatory of Theatre Arts & Film at SUNY Purchase did not go as well as Hartnett had hoped for, and a year later at age 19, he found himself in California. Shortly after arriving in Los Angeles, he caught an improbable break, landing a part in the short-lived but acclaimed drama Cracker, on ABC.
7. Although the series was cancelled after sixteen episodes, Hartnett had made a name for himself.
8. He was originally scheduled to play the role of Tino in Deuces Wild, but dropped out to star in Pearl Harbor.
9. Hartnett had been cast in the role five years before the film was produced, remaining committed to appearing in the movie because he liked the subject matter.
10. Among his 2007 roles were Resurrecting the Champ, a drama also starring Samuel L. Jackson, and the graphic novel-based 30 Days of Night, in which he played a small-town sheriff.
11. Hartnett described the second film as “supernatural, but kind of a western”.