Helmsley died of heart failure at her summer home in Greenwich, Conn., said her publicist, Howard Rubenstein.
Helmsley had faded from the spotlight in the last decade, a sharp departure from her 1989 tax evasion trial that provided an endless source sensational headlines.
Helmsley was remembered Monday by other leaders in the industry, including real estate tycoon Donald Trump, whose rivalry with Leona and her husband Harry was well-chronicled.
"Leona Helmsley was definitely one of a kind," Trump said. "Harry loved being with her and the excitement she brought and that is all that really matters."
Steven Spinola, president of the Real Estate Board of New York, noted that Helmsley was a player long before women were well-represented in the industry - when "this was an old boys' club."
Already experienced in real estate before her marriage, Helmsley helped her husband run a $5 billion empire that included managing the Empire State Building. She became a household name in 1989 when she was tried for tax evasion. The sensational trial included testimony from disgruntled employees who said she terrorized both the menial and the executive help at her homes and hotels.
That image of Helmsley as the "queen of mean" was sealed when a former housekeeper testified that she heard Helmsley say: "We don't pay taxes. Only the little people pay taxes."
She denied having said it, but the words followed her for the rest of her life.
Helmsley clearly enjoyed the luxury of their private fortune, flying the globe in the couple's 100-seat jet with a bedroom suite. The couple's residences included a nine-room penthouse with a swimming pool overlooking Central Park atop their own Park Lane Hotel; an $8 million estate in Connecticut; a condo in Palm Beach; and a mountaintop hideaway near Phoenix.
Their money supported charities, including New York-Presbyterian Hospital and its affiliated Weill Cornell Medical College, which received tens of millions of dollars, including a $25 million gift in 2006 to improve its treatment of digestive diseases.
Yet Helmsley nickel-and-dimed merchants on her personal purchases, stiffed contractors who worked on her Connecticut home and terrorized both menial and executive help at her homes and hotels, detractors say.
When her husband died in 1997 at age 87, Helmsley said in a statement: "My fairy tale is over. I lived a magical life with Harry."