A personal assistant to the 46-year-old actor is said to have found him dead at 11.30am this morning, a source told the New York Post, who are also reporting that Hoffman was found in the bathroom with a hypodermic needle still in his arm.
The cause of his death is currently unknown, but the Wall Street Journal reports that the office of the chief medical examiner and the New York police department are investigating.
He reportedly checked himself into rehab last year and has previously admitted battling a drug addiction in the past.
Hoffman is best known for his Oscar-winning turn as the titular character in Capote and most recently starred as Plutarch Heavensbee in The Hunger Games: Catching Fire.
His role as Lancaster Dodd in The Master also earned him an Oscar nod.
More details to follow"