Bernard Alfred "Jack" Nitzsche (/ˈniːtʃi/ NEECH-ee; April 22, 1937 – August 25, 2000) was an American musician, arranger, songwriter, composer, and record producer. He came to prominence in the early 1960s as the right-hand-man of producer Phil Spector, and went on to work with the Rolling Stones, Neil Young, and others. He worked extensively in film scores for the films Performance, The Exorcist and One Flew Over the Cuckoo's Nest. In 1983, he won the Academy Award for Best Original Song for co-writing "Up Where We Belong" with Buffy Sainte-Marie.

Nitzsche was born in Chicago and raised on a farm in Newaygo, Michigan, the son of German immigrants. He moved to Los Angeles in 1955 with ambitions of becoming a jazz saxophonist. He was hired by Sonny Bono, who was at the time an A&R executive at Specialty Records, as a music copyist. While there, Nitzsche wrote a novelty hit titled "Bongo Bongo Bongo". With Bono, Nitzsche wrote the song "Needles and Pins" for Jackie DeShannon, later recorded by the Searchers. His instrumental composition "The Lonely Surfer" entered the Cash Box top 100 on August 3, 1963, and reached No. 37.

He became arranger and conductor for producer Phil Spector, and orchestrated the Wall of Sound for almost all Spector's hits, perhaps best exemplified by "River Deep, Mountain High" by Ike and Tina Turner. Nitzsche worked with Earl Palmer, Leon Russell, Roy Caton, Glen Campbell, Carol Kaye and Hal Blaine in The Wrecking Crew, the backing band for many pop acts such as the Beach Boys and the Monkees. Nitzsche arranged the title song of Doris Day's film Move Over, Darling, which was a successful single on the pop charts of the time.

While organizing the music for the T.A.M.I. Show television special in 1964, he met the Rolling Stones and went on to play keyboards on their albums The Rolling Stones, Now! (The Rolling Stones No. 2 in the UK), Out of Our Heads, Aftermath and Between the Buttons as well as on their hit singles "Paint It, Black" and "Let's Spend the Night Together"; he also wrote the choral arrangements for "You Can't Always Get What You Want". In 1968 he introduced the band to slide guitarist Ry Cooder, a seminal influence on the band's 1969–1973 style.

On several Rolling Stones records, he was credited as player of the "Nitzsche-phone". In an obituary on Gadfly Online, former Rolling Stones manager Andrew Loog Oldham explained the credit:

I made that up for the credits on those Stones albums—it was just a regular piano (or maybe an organ) mic'd differently. It was all part of this package that was created around the Stones. People believed it existed. The idea was meant to be: "My god, they've had to invent new instruments to capture this new sound they hear in their brains." And they were inventing fresh sounds with old toys—therefore, it deserved to be highlighted—it was the read-up of creation, of imagination—getting credit for a job well done.

He collaborated with Neil Young, beginning with producing "Expecting to Fly" by Buffalo Springfield. In 1968, Nitzsche and Cooder co-produced Young's eponymous solo debut with David Briggs. As he was moving from baroque to folk and rock, Young hired Nitzsche for The Stray Gators, the session musicians behind Young on Harvest (1972) and Time Fades Away (1973).

With Crazy Horse in early 1970, Nitzsche played electric piano and, on the studio recording of "When You Dance, I Can Really Love," acoustic piano. Despite frequent clashes with Billy Talbot and Ralph Molina, Nitzsche remained with the band after Young left in 1970. Nitzsche co-produced the band's 1971 self-titled debut album and sang lead vocal on "Crow Jane Lady". He left Crazy Horse after the album's commercial failure.