George Chuvalo, the charismatic five-time Canadian heavyweight boxing champion who went the distance with Muhammad Ali twice and who was never knocked off his feet in 93 professional fights, died on Saturday, his 89th birthday.

The beefy, iron-jawed son of Croatian immigrants is generally acknowledged as one of the toughest men to have ever entered the squared circle.

He spent his last years in Toronto suffering from dementia after a career of head blows absorbed at the hands of some of the sport’s hardest punchers, among them knockout specialist George Foreman and Joe Frazier, who partly dislodged Mr. Chuvalo’s right eyeball from its socket at New York’s Madison Square Garden in 1967.

To the world, Mr. Chuvalo represented the quintessential hard-rock, indefatigable Canadian pugilist.

“You were a tough guy,” said boxing trainer and television personality Russ Anber. “You weren’t necessarily going to win, but you were going to hang in there with anybody in the world and you were going to give fans their money’s worth. George was that fighter.”