Arthur Stewart Farmer (August 21, 1928 – October 4, 1999) was an American jazz trumpeter and flugelhorn player. He also played flumpet, a trumpet–flugelhorn combination especially designed for him. He and his identical twin brother, double bassist Addison Farmer, started playing professionally while at high school in Los Angeles. Art gained greater attention after the release of a recording of his composition "Farmer's Market" in 1952. He subsequently moved from Los Angeles to New York, where he performed and recorded with musicians such as Horace Silver, Sonny Rollins, and Gigi Gryce and became known principally as a bebop player.

As Farmer's reputation grew, he expanded from bebop into more experimental forms through working with composers such as George Russell and Teddy Charles. He went on to join Gerry Mulligan's quartet and, with Benny Golson, to co-found the Jazztet. Continuing to develop his own sound, Farmer switched from trumpet to the warmer flugelhorn in the early 1960s, and he helped to establish the flugelhorn as a soloist's instrument in jazz. He settled in Europe in 1968 and continued to tour internationally until his death. Farmer recorded more than 50 albums under his own name, a dozen with the Jazztet, and dozens more with other leaders. His playing is known for its individuality – most noticeably, its lyricism, warmth of tone and sensitivity.