Walter (Killer) Kowalski, one of professional wrestling’s biggest stars and most hated villains when wrestlers offered a nightly menu of mayhem in the early years of television, died Saturday in Everett, Mass. He was 81.

Kowalski’s death was announced by his wife, Theresa, who said he had been hospitalized since a heart attack in early August.

At 6 feet 7 inches and 275 pounds or so, Kowalski was a formidable figure who delighted in applying his claw hold, a thumb squeeze to an opponent’s solar plexus, when he was not leaping from the top strand of the ropes and descending on his foe’s chest.

Emerging as a featured performer in the early 1950s, he became a TV celebrity with wrestlers like Antonino Rocca, Lou Thesz, Gorgeous George, Haystacks Calhoun and Nature Boy Buddy Rogers.

Kowalski wrestled on the pro circuits for some 30 years and appeared in more than 6,000 matches, by his count. Early in his career, he called himself Tarzan Kowalski. But, as he often related it, one particular match, at Montreal in the early 1950s, literally made his name.

“I was leaping off the rope, and Yukon Eric, who had a cauliflower ear, moved at the last second,” Kowalski told The Chicago Tribune in 1989. “I thought I missed, but all of a sudden, something went rolling across the ring. It was his ear.”

Yukon Eric was taken to a hospital, and the promoter asked Kowalski to visit him and apologize for severing his ear. Reporters were listening to their chat from a corridor.

“There was this 6-foot-5, 280-pound guy, his head wrapped like a mummy, dwarfing his bed,” Kowalski said.

“I looked at him and grinned. He grinned back. I laughed, and he laughed back. Then I laughed harder and left.

“The next day the headlines read, ‘Kowalski Visits Yukon in the Hospital and Laughs.’ And when I climbed into the ring that night, the crowd called out, ‘You animal, you killer.’ And the name stuck.”

Kowalski came to incur the wrath of the fans. As he told Esquire magazine in 2007: “Someone once threw a pig’s ear at me. A woman once came up to me after a match and said, ‘I’m glad you didn’t get hurt.’ Then she stabbed me in the back with a knife. After a while, I got police escorts to and from the ring.”

Walter Kowalski, his legal name, was born in Windsor, Ontario. His parents, Anthony and Marie Spulnik, had emigrated from Poland. He hoped to become an electrical engineer, but while he was working out at a Y.M.C.A., someone who was evidently impressed by his physique suggested he become a wrestler. He made his pro debut in the late 1940s.

He eventually tussled with all the famous names of wrestling, and in his later years he teamed with Big John Studd as a tag team called the Executioners.

“He was a hell of an attraction,” Thesz told The Pittsburgh Post-Gazette in 1998. “He had a great body back then. He was not a sophisticated wrestler, but every promoter wanted him because he made a lot of money.”

Kowalski retired in 1977 and founded Killer Kowalski’s School of Professional Wrestling in Malden, Mass. His protégés included the wrestlers Triple H and Chyna. He sold the school in 2003, and it is now in North Andover, Mass.

Kowalski married in 2006, his first marriage. In addition to his wife, of Malden, he was survived by a brother, Stanley Spulnik.

Beyond the ring, Kowalski displayed a gentle and even aesthetic side. He became a vegetarian in the mid-1950s, pursued charitable work for children with special needs and delighted in photographing fellow wrestlers. His work was sometimes displayed at galleries.

“I wanted to take action pictures,” he told The New York Times shortly after retiring. “But I went up to the ring, the fans screamed at me and threw garbage at me. It was detrimental to my health. So all I took were posed pictures. I sign my photographs Walter Kowalski. I used to be a villain, but now I’m a good guy. I kiss old women and pat babies. I’ve gone from Killer Kowalski to a pussycat.”