SAD NEWS ...COMEDIAN ROBIN WILLIAMS DEAD COMMITS SUICIDE

Beloved comic Robin Williams has committed suicide.

The comedian killed himself in Tiburon, in Northern California. 

According to the Marin County Sheriff's Office ... authorities found William's body inside his home.  They say he was found unresponsive.

He was unconscious and not breathing and the coroner suspects suicide due to asphyxia. 

Williams was last seen alive at his house at 10 PM Sunday night.

Robin went back to rehab last month to focus on his sobriety.  We're told alcohol was an issue.

Williams struggled with cocaine and alcohol abuse in the early '80s but was sober for 20 years. 

Robin's wife, Susan Schneider, says, "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."

President Obama has led the tributes to Robin Williams after the comic was found dead aged 63 from an apparent suicide, police in California said on Monday night.

President Obama offered up a touching tribute to the Oscar winner, praising his versatility as an actor.

'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.

As recently as this past July, Williams would reconnect with the 12-step program he's so often championed, this time during a brief stay at a Minnesota facility. 

Robin's last tweet was on July 31 ... wishing his daughter Zelda Rae a happy 25th birthday. He posted a #tbt instagram pic of himself holding her as a child. 

Williams was 63.