"She passed away peacefully" Tuesday night in her Manhattan apartment, said her son, director-writer-producer Christopher Hart, who was at her side. "She had such a wonderful life and a great long run. It was a blessing."
Hart was touring the country in her autobiographical one-woman show, "Here's to Life," until the pneumonia struck around Christmas, her son said. Broadway's theaters planned to dim their marquee lights Wednesday in honor of the longtime patron of the arts.
In 1991, she received the National Medal of Arts from the first President Bush. Hart's last gig was a December performance of her show in Atlanta.
David Lewis, Hart's longtime musical director, said she would be remembered "as the grande dame not only of show business but also in her philanthropy and her support for the American musical theater."
In addition to her star turn as Rosa Castaldi in the 1935 comedy "A Night at the Opera," Hart's other film credits included "She Loves Me Not" and "Here Is My Heart," both opposite Bing Crosby; Woody Allen's "Radio Days"; and "Six Degrees of Separation."
But she was probably best known as one of the celebrity panelists on the popular game show "To Tell the Truth." She appeared on the CBS prime-time program from 1956 to 1967 with host Bud Collyer and fellow panelists such as Polly Bergen, Johnny Carson, Bill Cullen and Don Ameche.
The show featured three contestants, all claiming to be the same person, with the panelists quizzing the trio to determine which one was telling the truth. Hart later appeared in daytime and syndicated versions of the show.
"People remember me from television," she once said. "They don't even remember me from `A Night at the Opera.' They have no idea that I played the lead and did all the singing. But they do remember television, particularly 'To Tell the Truth."'
She began her acting career on Broadway in "Champagne Sec" and went on to appear in many other Broadway productions, including the 1984 revival of "On Your Toes." In 1967 she made her operatic debut at the Metropolitan Opera in "Die Fledermaus" and created the role of Lucretia in the American premiere of Benjamin Britten's "Rape of Lucretia."
Hart's late husband was Pulitzer Prize-winning playwright Moss Hart, who wrote "You Can't Take It With You" and "The Man Who Came to Dinner" with George S. Kaufman. He won a Tony for directing "My Fair Lady" on Broadway.