He was found this morning at 11:30am by a screenwriter of a reported drug overdose.
According to officials, the friend called 911 immediately but he could not be resuscitated.
It is believed he was discovered with a needle in his arm in the bathroom of his apartment.
Mr. Hoffman's breakout role, however, was in 1997's "Boogie Nights." He also received accolades for his roles in high-profile films like 1998's "The Big Lebowski" and 1999's "Magnolia."
Hoffman won a Best Actor Oscar for his role in the 2005 film Capote.