His death was confirmed by his sister, Meg Peacocke.

"Richard Rodney Bennett: The Complete Musician" was the title of a 2010 biography, and few other figures in the arts have had so plausible a claim to distinction in such diverse genres.

Mr. Bennett wrote three symphonies, 17 concertos, five operas and dozens of elegant chamber works in a style that fused the avant-garde theories of Pierre Boulez, one of his teachers, with his own flexible, lyrical, nondogmatic approach.

He was an accomplished jazz pianist and singer who wrote and performed both songs and large-scale pieces. Three of his roughly 50 film scores were nominated for Academy Awards: "Far From the Madding Crowd" (1967), "Nicholas and Alexandra" (1971) and "Murder on the Orient Express" (1974), which won a Bafta award, the British equivalent of the Oscar, in 1975.

His taste had this wide range from the time he began listening to music on the radio as a child.

"When I came across something I liked," Mr. Bennett said in an interview with The Guardian in 2011, "I wanted to find out as much as I could about it. This was as true of hearing Hoagy Carmichael for the first time as it was later when I first heard Boulez. Being on a musical quest was something I always enjoyed."

Richard Rodney Bennett was born on March 29, 1936, in Kent, England, and grew up in Devon, where his family moved at the outbreak of World War II. It was a household receptive to artistic inclinations: his father wrote children's books and his mother was a pianist who had once studied composition with the British composer Gustav Holst.

Mr. Bennett's musical talents were clear early on. In a telephone interview Ms. Peacocke said that he began playing the piano around the age of 3. He first began writing down music — "lots and lots of what looked like arpeggios," she said — around 4. By 7 he was creating intelligible, playable pieces.

"I just scribbled away and eventually a C major chord was there," Mr. Bennett recalled. By the time he was 18 he had written three string quartets, and a year later he had finished his first film score.

He entered the Royal Academy of Music in London in 1953 and by his first summer had begun to attend the groundbreaking composition courses held in Darmstadt, Germany, where the participants included Luigi Nono and Karlheinz Stockhausen and the aesthetic ideology was uncompromisingly 12-tone. A scholarship from the French government gave Mr. Bennett two years of study in Paris with Mr. Boulez, another Darmstadt stalwart.

The forbidding severity cultivated at Darmstadt never came naturally to Mr. Bennett, whose music — influenced, perhaps, by the film scores he was writing all the while — adroitly blended the rigorous and the ingratiating. In a review of a revival of his 1965 opera, "The Mines of Sulphur," at the New York City Opera in 2005, Allan Kozinn wrote in The New York Times that Mr. Bennett "adopted 12-tone techniques to create angular vocal lines and spiky textures," and added, "But he was not after harshness as such: often his vocal lines soar, and they are supported by a vivid, lush and constantly moving orchestral score."

Mr. Bennett was appointed a Commander of the Order of the British Empire in 1977 and was knighted in 1998 for his service to music.

He is survived by Ms. Peacocke, a poet who publishes as M. R. Peacocke. She provided the texts for a series of her brother's vocal and choral works starting in the 1980s, including a surreally retro setting of her three-poem sequence "A History of the Thé Dansant," inspired by photographs of their parents from the 1920s.

Asked by the BBC in the early 1960s to write a work in the classical-jazz hybrid referred to, often derogatorily, as third stream, Mr. Bennett instead wrote a pure jazz piece, "Jazz Calendar." It was the first of many works, like a 1990 concerto written for the saxophonist Stan Getz (who died before he could perform it), that stood on their own as jazz and yet benefited from the tension between structure and freedom that he learned at Darmstadt, among other places.

"The different parts of my career seemed to take part in different rooms," he said in The Guardian interview, "albeit in the same house."