I was showing a collection of paperback book cover scans to a friend recently that were made by the artist Robert Maguire. A couple of them were spotted as being misattributed to him; a common mistake with so many cover illustrations not signed or credited. This forced me to sort through my collection and become more familiar with his work.
He has quickly become my favorite cover artist. I think you can see why with these examples. This site has a good biography about him: