James Minter (Jimmy) Knepper (November 22, 1927 – June 14, 2003) was an American jazz trombonist. In addition to his own recordings as leader, Knepper performed and/or recorded throughout his career with many of the top figures in jazz including the bands of Charlie Barnet, Woody Herman, Claude Thornhill, Stan Kenton, Benny Goodman, Gil Evans, Thad Jones & Mel Lewis, Toshiko Akiyoshi & Lew Tabackin, and, most famously, as friend and arranging/transcribing partner of bassist and composer Charles Mingus in the late 1950s and early 1960s. Knepper died in 2003 of complications of Parkinson's disease.