Williams won an Oscar for "Good Will Hunting." Getty Images / Henry S. Dziekan III Academy Award-winning actor and comedian Robin Williams has died at 63.

The cause of death is thought to be suicide by asphyxiation.

He was found unconscious in his home about noon on Monday.

Williams had reportedly been battling depression, according to a statement from his press representative. In July, Williams checked into a rehab center in Minnesota to "fine-tune" his sobriety.

Police were investigating the incident, and the coroner will conduct toxicology testing this week before making a final determination on cause of death, according to a release from the Marin County Sheriff's Office.

Williams was last seen alive in the home he shared with his wife about 10 p.m. Sunday.

Williams was known for his roles in "Mrs. Doubtfire," "Hook," and "Good Will Hunting," for which he won an Oscar as best supporting actor.

Williams had reportedly been working on a sequel to the popular "Mrs. Doubtfire" film. The original movie has become a family-comedy staple.

He got his breakout role in the 1978 sitcom "Mork & Mindy" in which he played an alien. The show was wildly popular:

Per @brianstelter: At its peak, #MorkandMindy drew 60 million viewers a week. To compare, this year's @AmericanIdol finale got 10 million. — Jeremy Hubbard (@JeremyHubbard) August 12, 2014



One of Williams' more dramatic roles was in "Dead Poets Society" in which he played an inspirational boarding-school teacher. He was nominated for an Oscar for his work on the film, which helped popularize the Latin phrase "carpe diem."

Williams did live comedy in addition to his on-screen work. The Los Angeles Times noted that Entertainment Weekly named Williams the "funniest man alive" in 1997.

Williams' wife, Susan Schneider, released this statement about his death:

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.

Williams' press representative, Mara Buxbaum, released this statement:

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 has been fairly open about his battles with alcohol and drugs. He got sober before the birth of his first son in 1983. Williams is survived by three adult children.