"Philip Seymour Hoffman,46, who won the Oscar for best actor in 2006 for his portrayal of writer Truman Capote in ‘Capote’ and created a gallery of other vivid characters, many of them slovenly and slightly dissipated comic figures, was found dead Sunday in his Greenwich Village apartment with what law enforcement officials said was a syringe in his arm, " reports the Associated Press.

The story adds, "The two officials told the Associated Press that glassine envelopes containing what was believed to be heroin were also found with Hoffman. Those items are being tested."

Chicago Sun Times columnist Richard Roeper wrote, " As a young man, Hoffman battled drug addiction, telling ’60 Minutes’ in 2006 that he would take ‘anything I could get my hands on,’ but said he went to rehab at age 22 and ‘got sober…You get panicked…I got panicked for my life. It was really just that.’ For two decades, Hoffman remained sober, but last May it was reported he had completed a 10-day detox program after he had started taking prescription pills. ‘[It] escalated to snorting heroin,’ said Mr. Hoffman. Mr. Hoffman had three children, ages 10, 7 and 5."

Some celebrities took to Twitter to express their saddness:

Susan Sarandon @SusanSarandon: Phillip Seymour Hoffman was a genius, brave and sweet. Can’t believe he’s gone. Huge loss. My deepest sympathy for his wife and children.

Kevin Bacon @kevinbacon: Oh what terrible news. What a talent. What a shame. #RIP

Steve Martin @SteveMartinToGo: Shocked to hear of Phillip Seymour Hoffman’s death. If you missed him as Willy Loman, you missed a Willy Loman for all time.

Katie Couric @katiecouric: Such a tragedy about Philip Seymour Hoffman… He was such a brilliant, talented actor. A huge huge loss for the world.

Kevin Smith ‏@ThatKevinSmith: This truly blows. PHILIP SEYMOUR HOFFMAN has died. First noticed him in SCENT OF A WOMAN. Brilliant actor. So sad…

Aaron Paul ‏@aaronpaul: We lost one of the greats today. Philip Seymour Hoffman RIP my friend. You will be missed always and forever.

Lena Dunham ‏@lenadunham: Beautiful beautiful man. We have lost so much joy to something so joyless. RIP PSH.

Ellen DeGeneres @TheEllenShow: Philip Seymour Hoffman was a brilliant, talented man. The news this morning is shocking and sad. My heart goes out to his loved ones.

Mia Farrow @MiaFarrow: OH NO!!!!! Philip Seymour Hoffman has died. A truly kind, wonderful man and one of our greatest actors – ever

Russell Brand @rustyrockets: Love and prayers for Philip Seymour Hoffman’s family. Addiction kills, I hope all who need it have access to abstinence based recovery.

Jon Favreau @Jon_Favreau: RIP Philip Seymour Hoffman. So sad. Such a great talent.

Harry Shearer @theharryshearer: Holy crap, Philip Seymour Hoffman passes away, decades too soon. One of the towering character actors of our time. RIP PSH.

Justin Timberlake @jtimberlake: Just hearing about Phillip Seymour Hoffman. Devastating. What an amazingly gifted actor. RIP

Evan Rachel Wood @evanrachelwood: I am sad on so many levels about the loss of Philip Seymour Hoffman. One of the greats. Losing him this way is absolutely tragic.

RainnWilson @rainnwilson: R.I.P. Philip Seymour Hoffman. One of the greatest, kindest actors who ever lived.

As previously reported, just last month, at the TCA press tour, Showtime had announced that Hoffman would be starring in a new comedy series titled "Happyish.’

Writes Nellie Andreeva at Deadline.com, "Of course, the news is so sudden and shocking, it will take time for Showtime brass to make a decision on the future of Happyish. But judging by the trailer from the pilot shown at TCA, Hoffman WAS the show. Here is how Showtime topper David Nevins introduced the project last month. ‘ "Happyish" is a very personal comedy starring one of the really great actors of our time, Oscar-winner Philip Seymour Hoffman. "Happyish" is about the fear — in this world of 25 year old CEOs and 27 year old billionaires — of becoming culturally irrelevant at a surprisingly young age. Hoffman plays Thom Payne, a successful but self loathing creative director at a New York ad agency.’

The story continues, " ‘Happyish’ actually got made largely because Hoffman agreed to do it. The script had been in the works at Showtime literally for years but was only greenlighted to pilot last summer after Hoffman agreed to star in after a very lengthy courtship."

Showtime released this statement about Hoffman’s death: “Philip Seymour Hoffman was one of our generation’s finest and most brilliant actors. He was also a gifted comedic talent. It was a great privilege and pleasure to work with him and we are all absolutely devastated by this sudden loss. Our thoughts go out to his family at this very difficult time.”

Hoffman is survived by his three children and their mother, Hoffman’s longtime girlfriend, Mimi O’Donnell, who is a costume designer, according to the New York Post.