"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," the Marin County Coroner said in a statement. "A forensic examination is currently scheduled for August 12, 2014 with subsequent toxicology testing to be conducted."
"Robin Williams passed away this morning," the actor's rep Mara Buxbaum added in a statement to ABC News. "He has been battling severe depression of late. This is a tragic and sudden loss."
Born in Chicago, Williams discovered his passion for acting in high school, before moving to New York City to study at Juilliard alongside Christopher Reeve.
A few years later, he also began doing stand-up comedy and working in television, before landing a star-making guest role as alien Mork in "Happy Days." In 1978, he was given his own spin-off series, "Mork & Mindy," for which he won a Golden Globe.
Around that time, Williams suffered a great loss: His friend, John Belushi, died of a drug overdose in 1982, prompting Williams, who had struggled with alcoholism and cocaine abuse, to quit, cold turkey. (Williams also said that the birth of his son in 1983 made him rethink things: "You realize, OK, now you have this responsibility, and [I] dealt with it," he told Nightline in 2011.)
He would go on to make two trips to rehab, once in 2006, and again this past July, which his rep told ABC News was "the opportunity to fine-tune and focus on his continued commitment, of which he remains extremely proud."
"It's [addiction] -- not caused by anything, it's just there," Williams told "Good Morning America" in 2006. "It waits. It lays in wait for the time when you think, 'It's fine now, I'm OK.' Then, the next thing you know, it's not OK. Then you realize, 'Where am I? I didn't realize I was in Cleveland.'"
Meanwhile, Williams discovered a passion for film in the '80s. With that came a litany of awards, including a Golden Globe for his role in the 1988 film, "Good Morning, Vietnam," a Golden Globe for his 1993 film, "Mrs. Doubtfire," and a Screen Actors Guild Award for 1996's, "The Birdcage." In 1998, after three nominations, he won his first Oscar for his role in "Good Will Hunting."
"This might be the one time I'm speechless!" he quipped while accepting the honor.
President Obama said in a statement on the actor's passing: "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 marginalized on our own streets."
Williams also had a rich personal life. In 1978, he married his first wife, Valerie Velardi, with whom he had one son, Zachary, now 31. He and Verlardi divorced in 1988, and the next year, he married Marsha Garces, who had previously been a nanny to Zachary. He and Garces, from whom he split in 2008, had two children, Zelda, now 25, and Cody, 23. Williams married his third wife, graphic designer Susan Schenider, in 2011.
Recently, Williams had been hard at work. He starred in the CBS series, "The Crazy Ones" and he recently finished filming several film projects, including "Night at the Museum: Secret of the Tomb." He also recently celebrated a birthday and, in his last Instagram post, wished his daughter a happy 25th.
"#tbt and Happy Birthday to Ms. Zelda Rae Williams!" he wrote. "Quarter of a century old today but always my baby girl. Happy Birthday @zeldawilliams Love you!"
According to the Marin County Coroner, officials received a 911 call at 11:55 a.m. Monday that Williams had been located unconscious and not breathing inside his residence in Tiburon, California. He was pronounced deceased at 12:02 p.m.
"An investigation into the cause, manner, and circumstances of the death is currently underway by the Investigations and Coroner Divisions of the Sheriff's Office," the statement read. "Preliminary information developed during the investigation indicates Mr. Williams was last seen alive at his residence, where he resides with his wife, at approximately 10:00 pm on August 10, 2014."
"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," his wife said in a statement. "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."