Some G.I. Joe fans point at Series VI (1987) as a turning point for the toy line moving away from the military background and into a more science fiction \ supernatural direction. Characters like Psyche-Out, Crystal Ball, and Raptor are common examples.
And yet, in Series II (1983) we got a guy with a steel plated head:
For Destro, all you really need is a bald guy with an open shirt, and Reaper Miniatures' Boris Barayev, Five Suns Smuggler (50002) really fits the bill.
I suppose I could have tried to green stuff on a little medallion for my version, but then maybe some things are better left undone.