Marty Feldman, 83, of Broomall, an acclaimed boxer with a withering knockout punch who went on to become a manager and trainer, died Tuesday, Feb. 14, of dementia at the home of his son David.

The 5-foot-10, 160-pound Mr. Feldman had an amateur boxing career that earned him a 37-2 record and the New Jersey Amateur Athletic Union middleweight title in 1952. His professional record from 1953 to 1962 was 23-2 (19 KO's). He fought out of Paterson, N.J.

To ring opponents, Mr. Feldman's knockout punch was something to be feared. It was known as the "Hammer of Thor," his family wrote in a tribute.

On Jan. 19, 1962, boxer Duke Johnson of Red Bank, N.J., absorbed a brutal right hook from Mr. Feldman during a bout in Gladiators' Arena in Totowa, N.J. The blow left Johnson paralyzed on one side, the Feldman family wrote. Mr. Feldman won by a technical knockout.

"As he racked up knockout after knockout, Feldman became a fan favorite," the boxing website BoxingRec.com reported. "Feldman seemed on his way to contention after compiling an undefeated log of 13-0 (13 knockouts)."

But back-to-back losses to obscure club fighters and the fact that he never earned more than $500 a match cooled his zest for fighting. Mr. Feldman retired in 1962 after a loss on points to Ronnie Geoffrion at Madison Square Garden.

Mr. Feldman started a second career as a trainer and fight manager. He often was called in by other promoters to train prospects, some of whom he molded into champions. They included "Cho-Cho" Brown (26-16-2), "Prince" Charles Williams (37-7-3), Paul Spadafora (49-1-1), and Tyrone Booze (22-12-2).

Other legends under his tutelage include Augie Pantellas (28-6) and Jack O'Halloran, whose performance plummeted after he left Mr. Feldman for another trainer, Mr. Feldman's family said.

In 2006, Mr. Feldman was inducted into the Pennsylvania Boxing Hall of Fame both as a middleweight and a trainer.

Born in Paterson but reared by his grandparents in New York City after his parents divorced, Mr. Feldman was a street scrapper. When an uncle gave him a pair of boxing gloves, he knew what he wanted to do.

"I always loved to fight," Mr. Feldman said in a July 25, 1994, Inquirer profile. "My grandparents would get so upset with me. I never started fights, but I liked them when they came."

After compiling an impressive amateur record, Mr. Feldman acceded to his grandparents' wish that he get an education. He attended the University of Denver and Fairleigh Dickinson University in Teaneck, N.J., but abandoned the classroom after two years because he preferred the gym.

As word spread of Mr. Feldman's death last week, Philadelphia boxing promoter J. Russell Peltz said, "I feel like crying."

"It was as a trainer that I knew him, working with fighters like Augie Pantellas, Frank 'The Animal' Fletcher, 'Prince' Charles Williams and Dave Tiberi and many, many others. We were as close as two people could be in this wonderful (?) business," Peltz posted online.

In later years, Mr. Feldman continued sports training at the family-owned Feldman Fitness Center in Springfield, Delaware County. He trained not only men, but also women with his Ladies Tone-Up program.

"A woman can do anything a guy can do," he told his family. He also assisted multiple sclerosis patients with severe arthritis by using gradual training techniques, his family said.

In 1968, he married Norma Dees. She died in 2006.

In addition to his son, a boxing promoter, Mr. Feldman is survived by son Damon and daughter Jennifer; seven grandchildren; and a brother.

Services were Sunday, Feb. 19. Interment was in Montrose Cemetery, Upper Darby.

Memorial gifts may be made to the Alzheimer's Foundation via www.alzfdn.org.