Gary Barnacle (born 1959) is an English saxophonist, flautist, brass instrument arranger, composer, and producer. Barnacle is primarily noted for his session work and live work, including various Prince's Trust concerts at Wembley Arena, the Royal Albert Hall and the National Exhibition Centre in Birmingham. He performed at the Nelson Mandela 70th Birthday Tribute at Wembley Stadium in 1988, and appeared on television and in music videos during the 1980s and 1990s with many popular music acts. He was also in a new wave duo called Leisure Process from 1982 to 1983 with ex-Positive Noise singer Ross Middleton.

Gary Barnacle was born in Dover, England in 1959.

Barnacle played the saxophone on several songs and albums by the Clash; he played on their album Sandinista! released on 12 December 1980 as a triple album, the single "This Is Radio Clash" released on 20 November 1981, and Combat Rock released on 14 May 1982. He was introduced to the Clash through their drummer Topper Headon, a school friend of Barnacle's and reportedly became involved in the Clash's infamous 1978 "pigeon shooting" incident.

Barnacle, trumpeter Luke Tunney, and trombonist Annie Whitehead played together on many sessions from 1979 to 1982, alongside Pete Thoms on trombone. Barnacle collaborated with the Ruts on their first two albums, both on Virgin Records: The Crack and Grin & Bear It. After their frontman, Malcolm Owen, was found dead from a heroin overdose on 14 July 1980, the band continued with Barnacle as Ruts D.C. (where "D.C." stands for the Italian term da capo) in a different musical vein. They released the album Animal Now in May 1981 on Virgin Records, before Barnacle departed following disagreements with the original Ruts, to be replaced by Dave Winthrop on Rhythm Collision released in July 1982 on Bohemian Records. Ruts D.C. split in 1983. During 1979–1980, he also contributed to M's debut album, New York • London • Paris • Munich, released in 1979 and to Sanity Stomp, released by Kevin Coyne in 1980.

In 1981, Barnacle contributed to the debut albums by Positive Noise: Heart of Darkness and Stray Cats. He also contributed to In Trance as Mission by Simple Minds, "Power and the Passion" by Midnight Oil, and played saxophone on Rick Wakeman's 1984. That year he also played saxophone on Black Snake Diamond Röle by former Soft Boys frontman Robyn Hitchcock. From 1990 to 1994, Barnacle toured with Level 42 and played on two of the band's albums: Guaranteed and Forever Now. The horn section he formed for Level 42, with British trumpet and fluegelhorn player John Thirkell, was known as the Hen Pecked Horns. Since then, Barnacle and Thirkell have provided the horn section for many recordings. Along with Thoms, they formed the Phantom Horns, one of the UK's horn sections which appear on a number of recordings from 1987 onwards.

In 1982, he and ex-Positive Noise singer Ross Middleton formed a synth-pop duo called Leisure Process. The band released four singles on the Epic label: two in 1982 ("Love Cascade" and "A Way You'll Never Be", which featured Mark King and Phil Gould of Level 42), and two in 1983 ("Cashflow" and "Anxiety"). All four singles were produced by Martin Rushent. In 1982, Barnacle also collaborated on Julien Clerc's Femmes, Indiscrétion, Blasphème, Mike Rutherford's Acting Very Strange, Marius Müller-Westernhagen's Das Herz eines Boxers, and with Visage's The Anvil. In 1984, his brother Steve was already in the band and Billy Currie and Dave Formula left; Barnacle and Andy Barnett replaced them for what would become Visage's Beat Boy album, which was released in September 1984 and yielded two singles, "Love Glove" and "Beat Boy". A decision to make Visage a live band instead of a strictly studio-based project failed and the band subsequently split in 1985.

In 1983, he contributed to Catch as Catch Can by pop singer Kim Wilde (whom he dated in the mid-1980s) and also to In Strict Tempo by Dave Ball and Private Dancer by Tina Turner. Barnacle later toured in Europe with Turner and participated in the recording sessions of her 1989 album Foreign Affair. He also appeared on the 1983 edition of Drama of Exile by Nico, where he also played the drums, "Right Now" by Siouxsie Sioux's second band the Creatures, Dalek I Love You's eponymous album, Jerky Versions of the Dream by Howard Devoto, Secret by Classix Nouveaux, Vocabulary by the Europeans, C'est C Bon by Carlene Carter, and Working with Fire and Steel by China Crisis, a collaboration that was repeated later in 1986 with the release of What Price Paradise. The year ended with the publication of the soundtrack for Educating Rita.

In 1984, Barnacle contributed to the recording sessions for This Is What You Want... This Is What You Get by Public Image Ltd, In the Long Grass by the Boomtown Rats, All the Rage by General Public, This Last Night in Sodom by Soft Cell, and Vermin in Ermine by Marc Almond and the Willing Sinners. He also performed on Olympia by Hong Kong Syndikat, Bite Black and Blues by Raoul and the Ruined, In on the Off Beat by Hey! Elastica and Influences, a solo album by Mark King of Level 42. Barnacle began a long collaboration with Elvis Costello, for whom he provided saxophone for Goodbye Cruel World. He also appears on many of Costello's compilation albums.