The actor was found dead at his home. Authorities found him unconscious, unresponsive and not breathing.
A coroner suspects the cause of death to be suicide due to asphysixia.
Robin was last seen alive at his home at 10pm on Sunday 10 August, TMZ has reported.
The comedy actor struggled with drug addiction during the 80s, but has been sober for the past 20 years.
He admitted himself to rehab earlier this year in order to focus on his recovery and sobriety.
Robin's wife, graphic designer Susan Schneider released a statement following his death.
She said: "This morning, I lost my husband and my best friend, while the world lost one of its most beloved artists andbeautiful human beings. I am utterly heartbroken."
Robin Williams a popular actor, well known for his roles in family films such as Mrs Doubtfire, Jumanji and Hook.
Closer Online will keep you updated as more details are released.