Jacob Benjamin Gyllenhaal is an American actor. Born into the Gyllenhaal family, he is the son of film director Stephen Gyllenhaal and screenwriter Naomi Foner, and the younger brother of actress Maggie Gyllenhaal. He began acting as a child, making his acting debut in
City Slickers (1991), followed by roles in his father's films
A Dangerous Woman (1993) and
Homegrown (1998). His breakthrough roles were as Homer Hickam in the biographical drama film
October Sky (1999) and as a psychologically troubled teenager in the science fiction psychological thriller film
Donnie Darko (2001).