He was a veteran of comedy shows including "Saturday Night Live" and Canada's homegrown "SCTV."
Rosato's former agent Larry Goldhar has confirmed that Rosato died Tuesday. Goldhar says an autopsy is being done.
The Italian-born actor joined Martin Short and Robin Duke as the only three performers to have been cast members of "Saturday Night Live" and "SCTV," which was spun out of Second City shortly after "SNL" launched in the mid-1970s.
In 2005, Rosato was charged with criminally harassing his wife. He spent two years in prison awaiting trial before he was diagnosed with Capgras syndrome, a condition that made him believe his wife and daughter had been replaced by impostors. He was committed to a mental institution.