Oscar-winning actor and comedian Robin Williams was found dead on Monday from an apparent suicide at his home in Northern California, Marin County Sheriff's Office said. He was 63. [Photo/Agencies]

Oscar-winning actor and comedian Robin Williams was found dead on Monday from an apparent suicide at his home in Northern California, Marin County Sheriff's Office said. He was 63.

The sheriff's coroner's division said it suspects the death was a suicide due to asphyxia, but the cause of death is still under investigation.

"This morning, I lost my husband and my best friend, while the world lost one of its most beloved artists and beautiful human beings. I am utterly heartbroken," Williams's wife Susan Schneider said in a statement.

Williams, who won an Academy Award for his role as a fatherly therapist in 1997's "Good Will Hunting," had been suffering from severe depression recently, his publicist Mara Buxbaum said.

Williams, who introduced his frenetic style on late 1970s TV series "Mork & Mindy" and had struggled with addiction in the past, had entered a Minnesota rehabilitation center last month to help him maintain sobriety.

Williams, who put all of himself into his charity work. Along with Billy Crystal and Whoopi Goldberg he was instrumental in turning Comic Relief into a thriving organization that has raised more than $50 million to help the homeless.

His representatives at the time said Williams was not using drugs or alcohol but had gone to the center to "fine-tune and focus" his sobriety after working a longer-than-usual schedule.

The Marin County Sheriff's office said it received an emergency call about noon local time on Monday, saying that Williams was unconscious and not breathing at his home near Tiburon, north of San Francisco.

President Barack Obama offered condolences to his family and said: "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."

Fellow comedic actor 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."

Comedian and talk show host Ellen de Generes tweeted: "I can't believe the news about Robin Williams. He gave so much to so many people. I'm heartbroken.