Buddy Bregman, an arranger and orchestra leader, works at a piano in Hollywood, Calif., in 1956. (Richard Tolbert/AP)

Buddy Bregman, a Hollywood musical arranger and conductor who worked alongside some of the top entertainers of the 1950s and 1960s and helped shape Ella Fitzgerald’s landmark “Song Book” albums celebrating the music of American tunesmiths such as Cole Porter and Richard Rodgers, died Jan. 8 at a retirement facility in Los Angeles. He was 86.

He had Alzheimer’s disease, said his son, Barry Bregman.

In a multifaceted career that included television and film production and writing a musical play, Mr. Bregman was best known for his work as a musical arranger and conductor.

Precocious and prolific, he scored a No. 1 hit for singer Gogi Grant in 1956 with his version of “The Wayward Wind.” Before he turned 30, Mr. Bregman had collaborated with dozens of celebrated performers, including Bing Crosby, Fred Astaire, Sammy Davis Jr., Rosemary Clooney, Jerry Lewis, jazz singer Anita O’Day and bandleader Count Basie. He wrote much of the music accompanying Bob Fosse’s choreography in the 1957 film “The Pajama Game.”

At 25, while playing tennis at the Hollywood home of Clooney and her husband, actor Jose Ferrer, Mr. Bregman met jazz impresario Norman Granz, who offered him a job with his record company. The label was known as Verve, and Mr. Bregman became something of a house arranger, creating the musical framework and writing the orchestrations for O’Day, Crosby and others.

When Granz signed Fitzgerald to his record, he wanted to showcase in an unprecedented way and hit on the idea of a series of albums featuring a single composer or composing. He asked Mr. Bregman to help select and arrange the music, beginning with the songs of Cole Porter.

“I picked every single song — in the afternoon in a darkened nightclub . . . on Hollywood Boulevard — me at the piano and Ella sitting on a bar stool next to me,” Mr. Bregman recalled in an undated interview with music producer Bruce Kimmel on the website HainesHisWay.com. “I would sing every song and then she would sing it back to me and probably halfway through we would either nod or shake or heads — we knew. This process took about a week of 5-hour days.”

Barry Bregman, a composer and music producer, recalled that Fitzgerald came to their house for rehearsals with his father.

In the end, Granz and Mr. Bregman decided to record 32 songs. Depending on the demands of the tunes, the arrangements were for string orchestra, a punchy big band or a small jazz ensemble.

The two-disc album was recorded over a three-day period in February, with Mr. Bregman conducting. “Ella Fitzgerald Sings the Cole Porter Song Book” became both a hit album and an artistic success. Six months later, they collaborated on follow-up album of songs by Richard Rodgers and lyricist Lorenz Hart. It was another triumph and helped Fitzgerald as one of the foremost interpreters of classic American song.

Mr. Bregman’s arrangements “gave her the pop edge that made the material accessible to a mass market without losing a jazz feel,” critic John McDonough wrote in liner notes for a 1993 reissue of the albums.

Other arrangers, including Nelson Riddle, Duke Ellington, Paul Weston and Billy May, collaborated with Fitzgerald on the remaining six albums in the project, but Mr. Bregman’s bracing arrangements were the first and rank among the best.

Collectively, the Fitzgerald “Song Book” recordings are now considered definitive renditions of hundreds of classic songs by Porter, Rodgers and Hart, Ellington, Irving Berlin, George and Ira Gershwin, Harold Arlen and Johnny Mercer.

Louis Isidore Bregman was born July 9, 1930, in Chicago. His father was a wealthy executive with a steel company, and his mother was the sister of renowned Broadway and Hollywood composer Jule Styne.

Young Buddy, as he was always known, learned piano and saxophone at an early age. He spent summers in Hollywood with his uncle, watching him compose music. He wrote his first orchestrations when he was 11.

He attended the University of California at Los Angeles but dropped out to focus on music. In addition to his work in the studios, Mr. Bregman became the musical director for singer Eddie Fisher’s television show from 1957 to 1959. He briefly had a show of his own in 1958 and later became the music director for singer Ethel Merman.

In the 1960s, Mr. Bregman turned to directing for television, including programs for Merman, Jonathan Winters and Danny Thomas. He later spent more than a decade in London, where he became a television producer for the BBC, largely of musical programs. He wrote a musical play, “Jump Jim Crow,” set in the Civil War-era South, for the Royal Shakespeare Co. in 1968.

Mr. Bregman’s first marriage, to actress Gloria Haley, ended in divorce. He was linked with many glamorous women in the 1950s and 1960s, including singer-actress Anna Maria Alberghetti, singer Peggy King and actress Mamie Van Doren. He was married to actress Suzanne Lloyd from 1961 until their divorce in 1988.

Survivors include his son from his first marriage, Barry Bregman of Valencia, Calif.; a daughter from his second marriage, Tracey Bregman, an Emmy Award-winning actress in “The Young and the Restless,” of Malibu, Calif.; four grandsons; and a great-grandson.

After trying to get various TV and film projects off the ground, with mixed success, Mr. Bregman returned in later years to music, composing arrangements for several recording projects.

He was considered master raconteur of Hollywood history, recalling the stars he admired (Crosby, Astaire, Merman) and others he found more difficult.

In 1956, he arranged and conducted “Rock-a-bye Your Baby With a Dixie Melody” for comedian Jerry Lewis.

“Working with him was a blast,” Mr. Bregman said. “When the record sold a million copies, Lewis said Mr. Bregman deserved a gold record, as well.

“So he did get me one: a black-and-white 8-by-10 glossy picture of the gold record! Enough said.”