According to police in Marin County, Calif., Williams was found "unconscious and not breathing" just before noon Monday inside his home in Tiburon, Calif., following a 911 phone call. He was pronounced dead at 12:02 p.m. after emergency personnel arrived. They added that the actor was last seen alive at 10 p.m. Sunday.
An investigation into the cause of the death is underway, but "the Sheriff's Office Coroner Division suspects the death to be a suicide due to asphyxia." A forensic examination is scheduled for Tuesday, along with a press conference that will be held at 11 a.m. in San Rafael, Calif.
Williams' publicist Mara Buxbaum told The Hollywood Reporter that Williams "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."
His wife, Susan Schneider, said: "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. On behalf of Robin's family, we are asking for privacy during our time of profound grief. 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."
Added David Steinberg, his manager of 35 years: "Nobody made the world laugh like Robin Williams. My brother, my friend, my soulmate, I will miss you."
Williams, a four-time Oscar nominee, won a supporting actor Oscar for Good Will Hunting for his portrayal of a wise and morose psychologist. He most recently starred in CBS' comedy The Crazy Ones, which lasted only one season. He was nominated for a People's Choice Award for his role as an advertising executive on the comedy, in which Sarah Michelle Gellar played his daughter.