Duke is a G.I. Joe team operative in the A Real American Hero line. First released as a Hasbro carded action figure in 1983, with 6 distinct figure versions produced across the 1982 to 1994 vintage run.
Duke appears in 13 episode synopses across the Sunbow (1983 to 1987) and DiC (1989 to 1992) runs, first appearing in Sunbow's "The M.A.S.S. Device, Part 1: The Cobra Strikes" (1983). Full screencap and continuity review pending.