J.J. Johnson (January 22, 1924 – February 4, 2001), born James Louis Johnson and also known as Jay Jay Johnson, was an American jazz trombonist, composer and arranger. Johnson was one of the earliest trombonists to embrace bebop.

After studying the piano beginning at age 9, Johnson decided to play trombone at the age of 14. In 1941, he began his professional career with Clarence Love, and then played with Snookum Russell in 1942. In Russell’s band, he met the trumpeter Fats Navarro, who influenced him to play in the style of the tenor saxophonist Lester Young. Johnson played in Benny Carter‘s orchestra between 1942 and 1945, and made his first recordings in 1943 under Carter’s leadership, recording his first solo (on “Love for Sale”) in October 1943. In 1944, he took part in the first Jazz at the Philharmonic concert, presented in Los Angeles and organized by Norman Granz. In 1945, he joined the big band of Count Basie, touring and recording with him until 1946.

While the trombone was featured prominently in dixieland and swing music, it fell out of favor among bebopmusicians, largely because instruments with valves and keys (trumpet, saxophone) were believed to be more suited to bebop’s often rapid tempos and demand for technical mastery. In 1946, bebop co-inventor Dizzy Gillespie encouraged the young trombonist’s development: “I’ve always known that the trombone could be played different, that somebody’d catch on one of these days. Man, you’re elected.”