He was 67.
"Joe Frazier was the embodiment of what a great heavyweight champion and person should be. He was a great gladiator," said Don King, who promoted Frazier's third bout with Muhammad Ali - dubbed the Thrilla' in Manila.
"When Smokin' Joe came to the ring, you knew you had someone who was coming to fight. I was proud to have known and promoted him, and I was honored to call him a friend."
A native of Beaufort, S.C. who later relocated and became symbolic of Philadelphia, Frazier won a gold medal in the 1964 Summer Olympics in Tokyo and turned pro the following year, stopping Woody Goss in one round in his debut at Convention Hall in Philadelphia.
He rose through the ranks to become champion in 1968, knocking out Olympic Trials foe Buster Mathis in 11 rounds to win consensus recognition in the absence of Ali, who'd been banned from the sport for refusing to report for military service.
The two men ultimately met and began their epic trilogy in 1971, when Frazier won a unanimous 15-round decision at Madison Square Garden. He defended twice more before a second-round KO loss to George Foreman in Kingston, Jamaica in January 1973.
"With Joe, first time we met, I extended my hand for a handshake," Foreman said. "He held back his hand and said, 'George, meet my wife.' After I greeted his Mrs., he then said, 'Hello' and 'Nice to meet you, George,' with a firm handshake. Nothing weak in his game. Everyone was the same.
"I knocked Joe down six times. When our fight was over, Joe was on his feet looking for me. It didn't matter the color of your skin. If you wanted to be friends, you could. Joe was willing to slam down anywhere, then a handshake after."
A second match with Ali in New York was a decision loss for Frazier in 1974, and was followed 21 months later by the rubber match in the Philippines, where Ali won by TKO when Frazier's corner would not allow him to come out for the 15th round.
Ali later described it as the "closest thing to death" he'd ever experienced.
Frazier fought just twice more after the last Ali fight, losing again by stoppage to Foreman eight months later and returning from a five-year hiatus for a 10-round draw with journeyman Floyd "Jumbo" Cummings in Chicago in 1981.
"Ali and Joe Frazier's rivalry is the king of all rivalries. You cannot mention Ali's name without Frazier, and you cannot mention Frazier without Ali," said WBC light heavyweight champion Bernard Hopkins, another Philadelphia fighter. "Their three fights were the three most exciting fights of the century.
"Joe is a person who will never be imitated or emulated. His legacy in boxing will never be duplicated, especially during his era. There will be only one Smokin' Joe Frazier."