Philip Seymour Hoffman has died from an "apparent drug overdose" in his New York City apartment, an NYPD spokesman said.
The 46-year-old Academy Award winner was found dead in the bathroom of his apartment at 11.30am local time (4.30pm GMT) on February 2.
Awarded a best actor Oscar for his role in the 2005 film Capote, Seymour Hoffman had checked into rehab in May for heroin use .
"He was found dead in his bathroom of an apparent drug overdose," an NYPD spokesman said.
Police were called to 35 Bethune Street in the West Village area of Manhattan by a friend of the actor, the spokesman said.
Seymour Hoffman was discovered with a syringe in his arm and "there was heroin found at the scene", the police official added.
The Office of Chief Medical Examiner will investigate the exact cause of death.
Seymour Hoffman had admitted struggling with drug addiction in the past but had reportedly been clean for 23 years before a relapse last year. "I went to rehab, I got sober when I was 22-years-old," he said in a 2006 interview. "You get panicked... and I got panicked for my life."
Seymour Hoffman's family said in a statement: "We are devastated by the loss of our beloved Phil and appreciate the outpouring of love and support we have received from everyone. This is a tragic and sudden loss and we ask that you respect our privacy during this time of grieving. Please keep Phil in your thoughts and prayers."
Photographers, television news crews and hundreds of members of the public gathered outside the actor's apartment.
The news of Seymour Hoffman's death came after claims that his representatives had denied a death hoax spread earlier in the week.
Born in Fairport, New York, in 1967, Seymour Hoffman got his first acting role in a 1991 episode of long-running police show Law And Order. He went on to play memorable characters in films such as The Big Lebowski, Boogie Nights and Magnolia and also had a distinguished career in the theatre.
The actor played Plutarch Heavensbee in the Hunger Games film Catching Fire, and was due to reprise the role in the last films, Mockingjay Parts 1 and 2. It is thought the actor had finished filming the first instalment but had work to complete on the second. But reports suggest the release of the movies will not be affected.
However, it seems Seymour Hoffman's upcoming television show Happyish might not continue.
An insider told E! News: "It is hard to imagine a way in which it could go on.His role would have to be recast and there weren't any other actors in serious consideration aside from Philip. If the show does move forward, the premiere would be delayed as pilot would need to be reshot."
The actor leaves behind his long-standing partner and costume designer Mimi O'Donnell and their two daughters and son.