Philip Seymour Hoffman was reportedly found dead in his Manhattan apartment this morning.
Law enforcement officials say the cause of death appears to be a drug overdose.
Hoffman was reportedly found by authorities with a syringe still in his arm and an envelope containing what appeared to be heroin.
Hoffman, 46, won the Best Actor Oscar in 2006 for his portrayal of Truman Capote in the 'Capote.'
Last year he revealed he had checked himself into rehab for snorting heroin.
Hoffman had struggled with drugs and alcohol in his twenties but remained sober since age 22 until this most recent relapse.
Hoffman has been in a longterm relationship with costume designer Mimi O'Donnell. They have a son, Cooper Alexander, born in March 2003, and two daughters, Tallulah, born in November 2006 and Willa, born in October 2008.