Bobby Hart, the songwriter and producer who, with partner Tommy Boyce, helped create the distinctive sound and chart success of the Monkees, has died. He was 86.

Hart died at his home in Los Angeles, his friend and co-author Glenn Ballantyne said. He had been in poor health after breaking his hip last year.

Boyce and Hart wrote several of the Monkees' best-known songs, including the TV group's theme, the No. 1 hit "Last Train to Clarksville" and the raucous "I'm Not Your Steppin' Stone." The duo also wrote the Monkees' "I Wanna Be Free" and the Top 5 single "Valleri," and contributed six songs to the million-selling debut album "The Monkees." They served as producers on many recordings and used their own backing band, the Candy Store Prophets, as session musicians.

Micky Dolenz, a member of the Monkees, credited Boyce and Hart with much of the group's early sound. In a foreword to Hart's 2015 memoir "Psychedelic Bubblegum," Dolenz wrote that he credited them "not only with writing many of our biggest hits, but, as producers, being instrumental in creating the unique Monkee sound we all know and love."

Don Kirshner, the music executive behind the Monkees project, tapped Boyce and Hart in the mid-1960s to supply songs for the television-made band that was openly modeled on the Beatles. The pair generated quick results: Hart later said that a misheard line in the Beatles' "Paperback Writer" inspired the guitar part for "Last Train to Clarksville." When Kirshner wanted a song with a female name, Boyce and Hart supplied "Valleri," which reached the Top 5.

Beyond their work for the Monkees, Boyce and Hart pursued their own recording careers, issuing albums such as "Test Patterns" and "I Wonder What She's Doing Tonite" and appearing on television series including "I Dream of Jeannie" and "Bewitched." They also wrote the theme to the daytime soap opera "Days of Our Lives."

The songwriting team engaged in political activity as well. They campaigned for Robert F. Kennedy during his 1968 presidential run and wrote the brass-tinged "L.U.V. (Let Us Vote)" in support of the 26th Amendment, which lowered the voting age to 18 in 1971.

In the decades after the Monkees' first run, Hart continued to write and collaborate with a range of artists. He co-wrote "Hurt So Bad," a hit for Little Anthony and the Imperials that was later covered by Linda Ronstadt, and worked on material for the Partridge Family. Hart and collaborator Austin Roberts co-wrote "Over You," performed by Betty Buckley in the film "Tender Mercies," which earned an Academy Award nomination. Hart also worked with Dick Eastman on songs for New Edition.

After Boyce and Hart split from their early roles with the Monkees and pursued separate projects, they reunited periodically on stage and in recordings. Hart toured with Monkees members Micky Dolenz and Davy Jones in the 1970s, and the four released the album "Dolenz, Jones, Boyce & Hart." Their contributions were chronicled in the 2014 documentary "The Guys Who Wrote 'Em." Boyce died in 1994.

Tommy Boyce and Bobby Hart

Hart was born Robert Luke Harshman in Phoenix, Arizona, and was the son of a minister. He described himself in his memoir as a shy child who found expression through music, learning piano, guitar and the Hammond B-3 organ by high school. After serving in the Army reserves, he moved to Los Angeles in the late 1950s to pursue work as a disc jockey before establishing himself as a songwriter and session musician.

He toured early in his career with Teddy Randazzo and the Dazzlers and, with Randazzo and Bobby Weinstein, helped write "Hurt So Bad." Hart shortened his name for professional use and formed a long-lasting creative partnership with Boyce, a singer-songwriter from Charlottesville, Virginia.

Hart was married twice, most recently to singer Mary Ann Hart, and had two children from his first marriage. His memoir and the documentary about Boyce and Hart brought renewed attention to the songwriting duo when the Monkees enjoyed a resurgence in the 1980s and later.

Hart's death marks the passing of a central figure in a pop phenomenon that combined television, recording and teen-idol appeal, and whose songs have been covered by artists as varied as Dean Martin and the Sex Pistols. His work helped define a sound that reached across charts and screens in the 1960s and beyond.