Jacob Benjamin "Jake" Gyllenhaal,born December 19, 1980 is an American actor. The son of director Stephen Gyllenhaal and screenwriter Naomi Foner, Gyllenhaal began acting at age ten. He has appeared in diverse roles since his first lead role in 1999's October Sky, followed by the 2001 indie cult hit Donnie Darko, in which he played a psychologically troubled teen and onscreen brother to his real-life sister, actress Maggie Gyllenhaal
In the 2004 science-fiction film The Day After Tomorrow he portrayed a student caught in a cataclysmic global cooling event, alongside Dennis Quaid as his father. He then played against type as a frustrated Marine in Jarhead (2005). The same year, he garnered critical acclaim and an Academy Award nomination for Best Supporting Actor as Jack Twist in the film Brokeback Mountain opposite Heath Ledger.
Gyllenhaal has promoted various political and social causes. He has appeared in Rock the Voteadvertising, campaigned for the Democratic Party in the 2004 U.S. Presidential election, promoted environmental causes, and campaigned on behalf of the American Civil Liberties Union.