James Louis "J. J." Johnson (January 22, 1924 – February 4, 2001) was an American jazz trombonist, composer and arranger. He was sometimes credited as Jay Jay Johnson. Johnson was one of the first trombonists to embrace bebop music. He has long been regarded as one of the leading trombonists of the post-swing era, exerting a pervasive influence on other jazz musicians.