Boxing legend and former middleweight champion Jake LaMotta — famous for his defiant endurance in the ring and for Robert De Niro’s Oscar-winning portrayal of him in the 1980 film “Raging Bull” — died late Tuesday at age 95.

“Rest in Peace, Champ,” De Niro said in a statement.

LaMotta died of complications from pneumonia in a nursing home near Miami, said his fiance of 15 years, Denise Baker, who called him a fighter to the end.

“He was a champ, all the way,” Baker told The Post. “A warm, wonderful man.”

The Lower East Side native who grew up in the Bronx logged 83 wins — including 30 knockouts — in a career that spanned the 1940s into the early ‘50s. Throughout, LaMotta was lauded for his iron jaw and ability to keep his footing despite the most brutal beatings.

His six-fight rivalry with Sugar Ray Robinson — long considered pound-for-pound the greatest fighter that ever lived — was legendary. LaMotta won only a single contest against Robinson, but it was Robinson’s first loss after 40 straight wins.

Until the end of his life LaMotta boasted that those other five fights were close ones, and that he never once hit the canvas.

“The three toughest fighters I fought were Sugar Ray Robinson, Sugar Ray Robinson and Sugar Ray Robinson. I fought Sugar so many times I’m surprised I’m not diabetic,” he once cracked.

But LaMotta didn’t just take punches.

“He was in some ways a much more sophisticated fighter than people give him credit for today,” author and boxing historian Thomas Hauser told The Post.

“He had a good jab. He knew how to attack and he also knew how to turn his head at the last minute to lessen the impact,” he said.

LaMotta’s life was also filled with controversy. He confessed in later years to having thrown one fight.

Married six times, he was brutal to his second wife, Vikki. And in the late ‘50s, he served six months jail for promoting the prostitution of a 14-year-old girl while running a bar in Miami.

“He beat Vikki very badly,” said Hauser, co-author of her memoir, “Knockout.” “He was a good fighter but he was a violent man,” added Hauser, whose upcoming “There Will Always be Boxing” is being published by the University of Arkansas press.

Still, thanks in large part to “Raging Bull” — Martin Scorsese’s directorial masterpiece — LaMotta will always be remembered for his fury and persistence.

“At first, he was afraid to hit me,” LaMotta once told The Post, recalling training sessions with De Niro from the late ‘70s, when the boxer was himself in his late ‘50s.

“Then I said to him, ‘Don’t worry about it. You can’t hurt me. I’m used to all these punches.”

The boxer trained the actor for a year, going a thousand rounds together.

“I gave him confidence that his punches wouldn’t be so bad. Then he went right at it. He changed overnight,” LaMotta told The Post.

“I don’t know how he did it … but when I got done with him, I’m sure he could have fought professionally. He was a natural.”

De Niro won Best Actor for the film.

“What a courageous fighter he was,” recalled Bruce Silverglade of Gleason’s Gym, where LaMotta trained and revisited over the past four decades, and where at least a half-dozen photos of him grace the walls.

“He fought to the finish,” Silverglade told The Post. “Until someone got knocked down.”

Indeed, LaMotta was only knocked down once, toward the end of his career, and went he into retirement soon after.

But in his 1940s heyday, LaMotta carved his niche as one of the toughest fighters in boxing — not the greatest, as his arch-nemesis, Robinson, is widely considered to be, pound for pound. But maybe the grittiest.

LaMotta’s three-to-one odds, underdog victory in 1943 against the highly-favored Robinson — he’d been written off in the seventh round, only to triumph in the 10th, giving Sugar Ray his first loss in a then forty-fight career — remains legendary.

“The whole neighborhood went nuts,” Alex Vicinanza, 84, remembered Wednesday of that night in The Bronx.

“I mean, the bars were packed that night,” Vicinanza remembered as he stood shopping at the Arthur Avenue Retail Market in Little Italy.

“People going into the street, throwing s—- all around. People went crazy.”

Recalled another Arthur Avenue old-timer, Valentino Reppucci, 86, “He was not as technical as Sugar Ray Robinson. But he was a puncher. I don’t know how he can absorb so many punches.”

“Incassatore,” the Italians would say in admiration. “E un buon incassatore” — “He can take a lot of punishment.”

“I had him along the ropes,” Robinson would remember of that losing bout in his autobiography. “He had his head down and I was really measuring him.

“His head popped up and he let go a left hook that almost tore through my stomach. It hurt so much, I had tears in my eyes, like a little kid . . . I learned that Jake LaMotta was some animal.”

Just as legendary is the 13-round bloody beating he withstood when he lost to Robinson six years later in the “Valentine’s Day massacre of February 14, 1951.

LaMotta would marry six times, and at the sixth wedding, “Sugar Ray Robinson, who had fought him six times, served as best man,” author Nick Tosches would note in his introduction to LaMotta’s memoir, “Raging Bull: My Story.”

In the memoir, the boxer describes how he once beat a bookie in the head with a lead pipe — then beat him again when, to his amazement and fury, he saw the bookie was still standing up.

“And finally he collapsed.”

“I never went to church, the priests couldn’t scare me with all that crap about hell, but somehow I knew, inside of me somehow I knew that I’d pay for it,” LaMotta’s memoir reads.

In the ring, LaMotta sought something akin to salvation by punishment.

Tosches quotes LaMotta from a 1970 interview: “I wanted to get punished and I took unnecessary punishment when I was fighting,” he explained.

“Subconsciously — I didn’t know it then, I realize it today when I know a little bit more about the mind and the brain — I fought like I didn’t deserve to live.”