Gary George Peacock was born May 12, 1935, in Burley, Idaho, and grew up in Yakima, Washington, where his father worked as a grocery-store business consultant. He tried piano, trumpet, and drums as a kid, but the moment that set his direction came at fifteen, when he attended a Jazz at the Philharmonic concert featuring Oscar Peterson and bassist Ray Brown. After graduating from Yakima High School in 1953 — while playing drums in his class band, no less — he had what he later described as an experience of "being played rather than playing," a certainty that music was going to be his life. He enrolled at the Westlake School of Music in Los Angeles, but the Army drafted him before he finished. Stationed in Germany, he was playing piano in a jazz trio when the group's bassist got married and quit; Peacock picked up the bass to fill the gap and never put it down, working sessions around Frankfurt well enough that, after his 1956 discharge, he stayed on in Europe for a stretch, playing with Hans Koller, Tony Scott, Bud Shank, and Attila Zoller before heading back to Los Angeles.

Westlake's scholarship program had folded by the time he returned, so Peacock went straight to work in the West Coast jazz scene, absorbing the vocabulary of Paul Chambers and Ray Brown and striking up a friendship with the young Scott LaFaro. Session work followed quickly — Barney Kessel, Art Pepper, Don Ellis's Essence, Clare Fischer's First Time Out and Surging Ahead, Prince Lasha's The Cry! — and he married fellow musician Annette Peacock, whose compositions he would keep returning to as a bassist for decades after their marriage ended. It was also during this period that he began what became a recurring, decades-spanning partnership with pianist Paul Bley, first documented on record in 1963 and eventually running to nine-plus albums into the late 1990s.

Peacock relocated to New York in 1962, and it was Ornette Coleman's music — initially bewildering to him — that reoriented his sense of what bass playing in a jazz group could be: "It challenged that fixed position I had about what jazz improvisation should be," he said later. "It created a pivot for me to embrace a much larger musical universe." In December 1963, that pivot led him into Bill Evans's trio alongside drummer Paul Motian, cutting Trio '64 for Verve — Peacock's only studio recording with Evans, and Motian's last. He then had a brief, high-visibility interlude the following spring: in April and May 1964, he subbed for Ron Carter in Miles Davis's working quintet. There's no studio recording to show for it, but Peacock spoke of it as a formative lesson in listening — Davis, he said, "didn't miss one thing. He heard everything."

That same year, 1964, put Peacock at the center of the emerging free-jazz vanguard: he joined saxophonist Albert Ayler's trio with drummer Sunny Murray, appearing on Spiritual Unity (recorded July 1964) and Ghosts (recorded that September in Copenhagen with Don Cherry added), and on New York Eye and Ear Control, a side-long free improvisation Ayler, Cherry, John Tchicai, and Roswell Rudd recorded as the soundtrack to a Michael Snow experimental film. Of Ayler, Peacock later said: "He brought something so genuine and natural and authentic... He was definitely a major influence for me." He was equally active elsewhere in the era's new-music ferment, appearing on Tony Williams's 1964 debut Life Time and continuing to record with Bley.

By the late 1960s, though, Peacock's momentum collided with a personal crisis. Struggling with substance dependency, he met Timothy Leary's circle and, at a friend's suggestion, tried LSD for the first time in Newton Center, Massachusetts. The experience knocked loose an identity he'd never questioned — musician, bass player — and left him, by his own account, without the desire to play. He stopped. What followed was a real sabbatical, not a metaphor: he threw himself into macrobiotics and Eastern philosophy, and eventually moved to Japan for two and a half years to study the language, history, and philosophy directly. He didn't stay away from the instrument entirely — in 1970, still based in Tokyo, he recorded Eastward with pianist Masabumi Kikuchi and drummer Hiroshi Murakami, and in April 1971 cut his first true leader date, Voices, with Kikuchi on piano. But when he returned to the United States, he still wasn't ready to commit to music full-time: he enrolled at the University of Washington in Seattle and spent roughly four years studying biology, graduating around 1976.

The pull back to jazz came, fittingly, through Paul Bley: a 1976 tour of Japan together, documented on the live album Japan Suite (recorded at midnight at a Yamaha festival that July), reignited something. The following February, in 1977, Peacock went into Generation Sounds Studios in New York with pianist Keith Jarrett and drummer Jack DeJohnette and recorded Tales of Another for the German label ECM — released under his own name, and, in hindsight, the founding document of one of the most important piano trios in jazz history. He also spent 1977 to 1983 teaching at the Cornish School of the Arts in Seattle while the partnership with Jarrett and DeJohnette quietly built toward something more formal.

That happened in January 1983: sessions at New York's Power Station yielded Standards, Vol. 1, Standards, Vol. 2, and Changes, released under Jarrett's name but crediting Peacock and DeJohnette as full equals. At a moment when a working band built around the American songbook read as artistically conservative, the "Standards Trio" instead treated those songs as open frames for improvisation — and the group toured and recorded together, on and off, for more than three decades, eventually amassing over twenty releases. A one-off variant is worth noting: 1994's At the Deer Head Inn paired Jarrett and Peacock not with DeJohnette but with Paul Motian, recorded at the small Pennsylvania club where Jarrett had played as a teenager (its complete recordings were reissued as a deluxe box set in 2025).

Peacock's own catalog kept running in parallel rather than pausing for the Standards Trio's success. He continued as an ECM leader through Voice From the Past — Paradigm (1982) and Guamba (1987), both built around Jan Garbarek; recorded duo albums with guitarist Ralph Towner (Oracle, 1994; A Closer View, 1998) and guitarist Bill Frisell (Just So Happens, 1994); reunited repeatedly with Paul Bley for albums like Partners, Annette, In the Evenings Out There, Mindset, and, alongside Paul Motian, Not Two, Not One and the much-later-released When Will the Blues Leave; and co-founded the trio Tethered Moon with pianist Masabumi Kikuchi and Motian, debuting in 1992. In the 2000s he formed an ongoing duo/trio partnership with pianist Marc Copland (What It Says, 2004, among others), and in 2009 and 2011 he was the connective figure on two notable quartet dates — Owl's Talk, pairing him and Motian with saxophonists Alexandra Grimal and Lee Konitz, and Enfants Terribles, a live Blue Note recording with Konitz, Frisell, and drummer Joey Baron. He also cut a duo album with pianist Marilyn Crispell, Azure, in 2011 (released 2013).

His final chapter as a leader arrived with the Gary Peacock Trio, formed with Copland and Baron: Now This (2015) and Tangents (2017), both for ECM, both recorded in Europe. Tangents proved to be his last album as a leader. The Standards Trio's active life effectively ended in February 2018, when Keith Jarrett suffered the first of two strokes that ended his performing career; ECM released the archival concert recording After the Fall — captured live in 1998, held back for two decades — that same March. Peacock died at his home in Olivebridge, in New York's Hudson Valley, on September 4, 2020, at eighty-five. ECM founder Manfred Eicher called him "a life-long friend, and a musician whom I had admired greatly since the first time I heard him." Peacock had spoken, in his later years, of treating his daily practice with the instrument as an extension of zazen — sitting meditation — a discipline of attention rather than a technique to be mastered.

Peacock's early vocabulary drew on Paul Chambers and Ray Brown, but it was his friendship with Scott LaFaro and his subsequent immersion in Ornette Coleman's music that reoriented him toward treating the bass as a fully melodic, harmonically independent voice rather than a purely time-keeping one — an approach he carried directly into his work with Bill Evans and, more radically, into Albert Ayler's free-jazz trio. His years-long partnership with Paul Bley pushed that idea further, reimagining the piano trio as a three-way conversation among equals, a model that shaped how Keith Jarrett would later build the Standards Trio around him. Peacock's own account of his late-career discipline — daily, deliberate attention to posture, breathing, and the instrument itself, framed explicitly through zazen practice — points to a musician for whom technical freedom and a kind of meditative selflessness were never separate pursuits.