The death of American actor and comedian Robin Williams has drawn a flood of tributes to a man being described as a genius.
Police say Williams died at his home in Tiburon, northern California, of asphyxia in an apparent suicide on Monday. He was 63.
US President Barack Obama led the tributes, describing the actor as "one of a kind." Making reference to his many roles, Mr Obama, said: "Robin Williams was an airman, a doctor, a genie, a nanny, a president, a professor, a bangarang Peter Pan and everything in between. "
"Williams 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 Oscar-winning actor had struggled with drug and alcohol addiction in the past and entered a rehabilitation centre recently to help him stay sober, amid bouts of serious depression.
In a statement, Williams' wife Susan Schneider said she was "utterly heartbroken". "As he is remembered, it is our hope the focus will not be on Robin's death, but on the countless moments of joy and laughter he gave to millions."
His publicist released a statement, reported by Entertainment Weekly, that said: "Robin Williams passed away this morning. He has been battling severe depression of late. This is a tragic and sudden loss. The family respectfully asks for their privacy as they grieve during this very difficult time."
Williams married three times, most recently in 2011 to Ms Schneider, and has three children.
Steven Spielberg, who directed Williams as Peter Pan in the 1991 film Hook, said he was a lightning storm of comic genius, while another director Phillip Noyce called him one of the greatest comedians of all time.
Fellow funny man Steve Martin said in a tweet: "I could not be more stunned by the loss of Robin Williams, mensch, great talent, acting partner, genuine soul."
Actor Johnny Depp added this tribute:
New Zealand film-maker Vincent Ward said he became friends with Williams during the shooting of his 1998 film What Dreams May Come and paid tribute to a kind, thoughtful and very funny man.
"Most of the time he was a very quiet man. The thing about humour is with comedians it comes from a place of often darkness and it's a way of somebody relieving themselves of whatever they're going through. They go to this dark place and come up with this wild material and it's their way of coping. I guess that was very much true of Robin."
Hollywood entertainment journalist Jeannie Wolf said he was a comedian people loved. "The audience loved Robin Williams. Anybody who ever worked with him loved him."
Comedy clubs in the US are holding a silent tribute on Monday night in his memory.
Zany comedian and serious actor
Born in Chicago, Illinois in 1951, Robin Williams joined the drama club in high school and was accepted into Juilliard School in New York, the prestigious American academy for the arts, where was encouraged by a teacher to pursue comedy, the BBC reports.
The actor was first known for his zany portrayal of an alien in the 1970s television show Mork and Mindy.
Williams was a regular stand-up comedian while continuing to act in such films as Good Morning Vietnam, Dead Poets Society, Mrs Doubtfire and as the voice of the genie in Aladdin. While many of his roles were in comedies, Williams won the Oscar in 1998 for best supporting actor as a therapist in Good Will Hunting.
The actor had struggled with addiction in the past and in July this year entered a Minnesota rehabilitation centre to help him maintain sobriety, Reuters reports.
His representatives at the time said he was not using drugs or alcohol but had gone to the centre to "fine-tune and focus" his sobriety after working a longer-than-usual schedule.