Which classic science fiction or fantasy author is due for a comeback?

Science fiction and fantasy readers are constantly questing for new realms and new ideas — but sometimes, some of our greatest authors and creators get left by the wayside as a result. Which classic author (living or dead) do you think deserves a new appreciation?

Make your case below — and please include a nice book cover or other image, because it's nice to have pictures along with blocks of text.

Top image: Cover detail of A Spectre is Haunting Texas by Fritz Leiber.