The victim of a death hoax, grim news of his own mortality was confirmed by police in New York on Sunday evening, caused by an apparent drug overdose.
Seymour Hoffmann made his name in the 1990s in films including cult classics Boogie Nights and the Big Lebowski.
He later won the best actor Oscar - and a legion of fans - for his 2005 role in the film Capote, in which he played the title character, writer Truman.
Throughout his career he featured in independent films as well as staring alongside Hollywood A-listers such as Tom Cruise in the blockbuster Mission Impossible III.
And more recently he appeared on the silver screen playing the part of Plutarch Heavensbee, the head games-maker in the dystopian Hunger Games franchise.
Indeed he was last seen in British cinemas performing in the second instalment of the saga, released at the end of last year.
Seymour Hoffman was due to reprise the role for the forthcoming concluding part of the trilogy.
The 46-year-old's screen presence won him many admirers, with colleagues describing how his roles illuminated the pictures in which he appeared.
But his addictions were the hidden backdrop to his successes and accomplishments.
Last year father-of-three Seymour Hoffman revealed he was seeking treatment for drug abuse, and he checked into rehab in May for heroin use.
He told celebrity news website TMZ he had been taking prescription drugs and, briefly, heroin before seeking help.
It came after more than two decades of being clean from drugs.
The actor leaves behind his long-standing partner and costume designer Mimi O'Donnell and their two daughters and son.