Over the years Williams' career brought him to Toronto on multiple occasions, filming movies in the city and in 2012 he came to the Sony Centre for "sitdown therapy" with Canadian comedian David Steinberg.
"Terribly saddened by the tragic loss of Robin Williams — a rare and inspired genius," Second City Toronto tweeted Monday night.
"I know he struggled with depression. He was just hilarious. Hands down one of the funniest actors," a fan told CBC News on her way into a Second City show in Toronto, upon hearing the news.
His fans in Toronto recalled many memorable encounters with Williams, whether seeing him on stage or on the street.
Robin Siegerman posted a message on Facebook about the time she had a chance to talk to the legendary comedian after he performed a live show in Toronto.
When it was revealed they shared the same name, Siegerman got to experience "five zany minutes" of Williams riffing on the fact they were both named after a bird and a superhero’s sidekick.
"I'm so sad," Siegerman wrote online. "Good night Robin. I hope your pain is finally silent."
A group of Second City students outside the Mercer Street theatre on Monday night all said they were shocked to hear about Williams' death, agreeing that he was an inspiration to them because of his intense energy.
The majority of fans entering the theatre, when asked how they will remember Williams the most, said with enthusiasm, "Mork and Mindy!"
Local fans were also sharing their admiration for Williams, their stories about him and their expressions of sadness online.
On mobile? See fan tweets here.
At least two of Williams' films had some production work in Toronto — Death to Smoochy and Man of the Year, the latter of which had at least one scene that was shot at the CBC building on Front Street.
Ontario Health Minister Eric Hoskins tweeted his memory of meeting Williams when his wife, Samantha Nutt, was pregnant and Canadian tennis star Eugenie Bouchard tweeted, "Mrs. Doubtfire was my childhood."
Williams, 63, was pronounced dead at his San Francisco Bay Area home, according to the sheriff's office in Marin County, north of San Francisco. The sheriff's office said the preliminary investigation shows the cause of death to be a suicide due to asphyxia.
The Marin County coroner's office said Williams was last been seen alive at home at about 10 p.m. Sunday. An emergency call from his house in Tiburon was placed to the Sheriff's Department shortly before noon Monday.