Jim Sachs is probably the most well known artist on the Amiga. Not only because he created breathtakingly beautiful graphics for games like Defender of the Crown and Ports of Call, but also because he created a lot of promotional art and magazine covers that were re-used all over the place to promote the Amiga.
He concentrated on architecture while in colledge, but went to the Air Force to fly C-141 Starlifter cargo planes after graduating.
After that he got into computer graphics through the C64 and then switched to the Amiga when that came out.
Amazing Computing interview (1987)
Amazing Computing interview (1994)