These covers by Bill Sienkiewicz are a good chronology of his artistic development through the 80s and 90s. He's done only a handful of full interior art projects in his career (he's done a surprising amount of interior inks over other pencilers, however) but he's done countless covers it feels like. He started out as a pretty traditional Neal Adams disciple but then morphed into something a lot more avant-garde (at least for mainstream comics) over time. HIs covers are always arresting, often iconic, and definitely always him.