Guy Barker (born 26 December 1957) is an English jazz trumpeter and composer. Barker was born in Chiswick, London, the son of an actress and a stuntman. He started playing the trumpet at the age of twelve, and within a year had joined the National Youth Jazz Orchestra. After lessons from Clark Terry in 1975, Barker went on in the 1980s to play with John Dankworth, Gil Evans (with whose orchestra he toured and recorded in 1983), Lena Horne and Bobby Watson.

Barker was a member of Clark Tracey's quintet from 1984 to 1992, and continues to play with Tracey, as well as with Tracey's father Stan. As a sideman he has played with many major musicians, including Ornette Coleman, Carla Bley, Georgie Fame, Mike Westbrook, Frank Sinatra, Colin Towns, Chris Hunter, Mike Oldfield, Cleo Laine, and XTC.

He leads his own band, featuring an international mix of musicians – Perico Sambeat (alto saxophone; Spain), Bernardo Sassetti (piano; Portugal), Geoff Gascoyne (bass, United Kingdom), and Gene Calderazzo (drums; United States) – for which Barker also composes.