Robin Williams has been found dead in his California home at the age of 63. The actor, who is best known for his comical roles in Good Morning, Vietnam and Mrs. Doubtfire, has recently been battling with severe depression according to his press representative.
Police suspect the death may have been suicide. He was pronounced dead at 12.02pm after police were called to the home at around 11.55am local time.
A Marin County Sheriff's Office statement said: "At this time, the Sheriff's Office Coroner Division suspects the death to be a suicide due to asphyxia, but a comprehensive investigation must be completed before a final determination is made."
US president Barack Obama paid tribute to the star: "Robin Williams was an airman, a doctor, a genie, a nanny, a president, a professor, a bangarang Peter Pan, and everything in between. But he was one of a kind.
"He arrived in our lives as an alien - but he ended up touching every element of the human spirit. He made us laugh. He made us cry. He gave his immeasurable talent freely and generously to those who needed it most - from our troops stationed abroad to the marginalised on our own streets.
"The Obama family offers our condolences to Robin's family, his friends, and everyone who found their voice and their verse thanks to Robin Williams."
Steven Spielberg, who worked with Williams on Hook, said: "Robin was a lightning storm of comic genius and our laughter was the thunder that sustained him. He was a pal and I can't believe he's gone."
Steve Martin, who appeared alongside Williams in a 1988 theatre production of Waiting for Godot, said: "I could not be more stunned by the loss of Robin Williams, mensch, great talent, acting partner, genuine soul."
Williams' Good Will Hunting co-star Minnie Driver said: "My heart's broken. Robin was a beautiful, kind soul. Can't bear that he's gone. So incredibly sorry for his family."
Talk show host Ellen DeGeneres tweeted: "I can't believe the news about Robin Williams. He gave so much to so many people. I'm heartbroken."
Graham Norton, who had interviewed Williams on his BBC chat show, said: "Such sad news. My heart goes out to his family. The great Robin Williams."
Jonathan Ross, who had also interviewed the actor, said: "Robin Williams is gone. I loved him. Incredibly talented performer. Wonderfully sweet and generous person. Heartbreaking news. So sad.
"What a devastating loss."
Kevin Spacey, who was in the 2009 film Shrink alongside Williams, tweeted: "Robin Williams made the world laugh & think. I will remember & honor that. A great man, artist and friend. I will miss him beyond measure."
Actress Mara Wilson, who played Williams' daughter in Mrs Doubtfire, said: "Very sad, very upset, very glad I did not have to hear about this through Twitter. Probably going to be taking some time off it for a while."
Police are expected to release more information about his death at 7pm British time today.