From 
infoplease:
Jake GyllenhaalActorBorn:  19 December 1980
Birthplace:  Los Angeles, California
Best known as:  The star of 
Donnie Darko and 
Brokeback MountainJake Gyllenhaal's turn as a rocket-loving youngster in 1999's 
October Sky moved him directly into the Hollywood category of hot young actors to watch. It led to more memorable parts in the spooky sci-fi hit 
Donnie Darko (2001, co-starring his sister, Maggie) and 
The Good Girl (2002, with Jennifer Aniston). 
Blue-eyed and with usually tousled 
brown hair, Gyllenhaal has a standout 
gawky charm that makes up for a lack of classical movie-star looks. The son of director Stephen Gyllenhaal, he has been in and around movies since he was a kid (he played Billy Crystal's son in 1991's 
City Slickers). He starred in the drama 
Moonlight Mile (2002, with Dustin Hoffman and Susan Sarandon) and the global-warming disaster movie 
The Day After Tomorrow (2004). In 2005 he played a Marine fighting the Gulf War in 
Jarhead and co-starred with Heath Ledger in 
Brokeback Mountain, the much-discussed "gay cowboy movie" directed by Ang Lee.