"He was a true musical genius, but above all that, he was a beautiful human being. I will truly miss him," said Barbra Streisand, who met the composer in 1963 and sang his "The Way We Were" to a Grammy win in 1974. "It was his brilliantly quick mind, his generosity, and delicious sense of humor that made him a delight to be around."
Mr. Hamlisch's award-winning career included three Academy Awards, four Emmys, four Grammys, a Tony, and three Golden Globes.
He was one of the candidates being considered to lead the Philly Pops after Peter Nero's departure and had signed to lead the Pops next spring in a three-concert program of music from the James Bond films.
He "was being considered to be our principal conductor at the end of the [2012-13] season, which is Peter Nero's final season," Philly Pops president Frank Giordano said Tuesday. "He certainly was a top choice because he was at the top of his field."
The onetime child prodigy's music colored some of the most important works of Hollywood and Broadway.
He composed more than 40 film scores, including for Sophie's Choice, Ordinary People, The Way We Were, and Take the Money and Run. He won his third Oscar for his adaptation of Scott Joplin's music for The Sting.
On Broadway, Mr. Hamlisch received a Tony and the Pulitzer Prize in 1976 for A Chorus Line and wrote the music for The Goodbye Girl and Sweet Smell of Success.
Mr. Hamlisch also reached into the pop world, writing the No. 1 R&B hit "Break It to Me Gently" with Carole Bayer Sager for Franklin. He won Grammys in 1974 for best new artist and song of the year, "The Way We Were," performed by Streisand.
"He was classic and one of a kind," Franklin said after learning of his death, calling him one of the "all-time great" arrangers and producers. "Who will ever forget 'The Way We Were'?"
Mr. Hamlisch's interest in music started early. At 7 he entered the Juilliard School of Music, stunning the admissions committee with his renditions of "Goodnight Irene" in any key it desired.
In his autobiography, The Way I Was, he admitted living in fear of not meeting his father's expectations. "By the time Gershwin was your age, he was dead," the Viennese-born musician would tell his son. "And he'd written a concerto. Where's your concerto, Marvin?"
In his teens, he switched from piano recitals to songwriting. Show music held a special fascination for him. His first important job in the theater was as rehearsal pianist for the Broadway production of Funny Girl with Streisand in 1964.
"Maybe I'm old-fashioned," he told the Associated Press in 1986. "But I remember the beauty and thrill of being moved by Broadway musicals - particularly the endings of shows. The end of West Side Story, where audiences cried their eyes out ."
Although he was one of the youngest students ever at Juilliard, he never studied conducting.
"The Way We Were" exemplified his old-fashioned appeal - a big, sentimental movie ballad that brought huge success in the rock era. He was perhaps even better known for his work adapting Joplin on The Sting - in particular, "The Entertainer," the movie's theme song, which is to this day blasted by ice cream trucks.
Mr. Hamlisch was principal pops conductor for symphony orchestras in Pittsburgh, Milwaukee, Dallas, Pasadena, Seattle, and San Diego at the time of his death.
Giordano, president of the Philly Pops, said Mr. Hamlisch "was going to be our guest conductor for our April 'Bond and Beyond' program. He composed The Spy Who Loved Me and he wrote the Carly Simon song, 'Nobody Does It Better,' " for the film. The hit single was nominated for an Oscar in 1977.
A new work by Mr. Hamlisch, The Nutty Professor, was in performances in Nashville at the time of his death, and he also was working on another musical, Gotta Dance. He also had written the score for a new HBO film on Liberace, Behind the Candelabra.
He is survived by his wife of 25 years, Terre.
Inquirer staff writer Tirdad Derakhshani contributed to this article.