Geez, I love Marshall's caricatures. They look like they were done on Photoshop, but they're from the early 1990s and I think they derive from darkroom manipulation and prismacolor enhancement.
Marshall did these when there weren't very many people in the computer caricature field. Interesting, huh? (Marshall deserves a much better intro than this but I'm so sick from medication that I can hardly keep myself from falling off the chair I'm sitting on.)