Complex sentence: One of the trademarks of Stevens'comedy albums were the cover photos, where, for example, he's dressed up as Napoleon Bonaparte, Humpty Dumpty, or General Douglas MacArthur.
Split into simpler sentences: One of the trademarks of Stevens'string of comedy albums were the photo shoots. For example, on one album he's dressed up as Napoleon Bonaparte, on another he's Humpty Dumpty, and on another he's dressed as General Douglas MacArthur.