Legaux died of pancreatic cancer Monday at his home in Palm Springs, said Al Honore, his longtime business partner.
Harold & Belle's was established on West Jefferson Boulevard in 1969 by New Orleans transplants Harold and Belle Legaux as a small restaurant and bar.
The same year, Harold Jr. and his wife, Denise, opened a small hamburger stand called Hungry Harold's on Slauson Avenue. They took over operating Harold & Belle's in 1982, three years after Harold Sr. died.
The restaurant underwent a major renovation in 1984, in which the dining and kitchen area were expanded.
"And we expanded the menu as we grew," said Honore, who became Legaux's business partner in 1984.
"He was an extremely particular food person, with quality and consistency, and he was as fine a restaurant operator as any major restaurateur in Los Angeles," Honore said.
The popularity of the 150-seat restaurant extends to sports, entertainment and political figures, who show up to dine on its po' boy sandwiches, gumbo, seafood platters and red beans and rice.
When Harold & Belle's celebrated its 40th anniversary in 2009, more than 500 patrons turned out for the restaurant's block party.
At a VIP luncheon and press briefing for city and county officials and other dignitaries at the restaurant the day before, Mayor Antonio Villaraigosa proclaimed that it served "the best gumbo in town."
Radio and television host Tavis Smiley, who was host of the event, told The Times on Thursday that he has been a regular at Harold & Belle's since arriving in Los Angeles in 1985 and was serving as a young aide to then-Mayor Tom Bradley, who introduced him to the restaurant and the family.
"Harold & Belle's is an iconic institution in our community," said Smiley, noting that he has eaten there "more times than I can count and more times than my calorie count can allow.
"Quite frankly," he said, "because of racism and because of it not being a priority at City Hall, that part of the city has been neglected for so many years in terms of infrastructure and in terms of economic opportunity, so to have a family that has remained dedicated to that community for all these years is something to celebrate.
"So that's why I celebrate Harold's life and legacy. His life and legacy, in essence, is about love and service to everyday people. He loved the community, and he served it well."
Los Angeles County Supervisor Mark Ridley-Thomas is another longtime fan of the restaurant.
"For years, I've gone to Harold & Belle's to discuss business, talk politics or to celebrate family occasions," he said in a statement Thursday. "After a bowl of Legaux's world-famous gumbo — followed up by the bread pudding — you couldn't leave feeling anything but satisfied.
"But for South Los Angeles, where top-notch dining experiences are scarce, Legaux's restaurant is more than just a place to eat; it is also a source of community pride.... I dare say that it is the most well-regarded and well-supported restaurant in the African American community."
Legaux, who was born in Los Angeles on Aug. 17, 1949, is survived by his wife; a daughter, Brandy LeForbe; a son, Ryan; his mother, Belle; two sisters, Gayle Deruise and Marie Ruffo; and a grandson.
A funeral service will be held at 10:30 a.m. Monday at St. Bernadette Catholic Church, 3825 Don Felipe Drive, Los Angeles.