The cartoonist Charles "Chas" Addams (1912-1988) is, of course, best remembered for the family bearing his name which he created in a series of cartoons for the New Yorker. The various characters who shared a haunted house, originally without names but given them for the spin-off TV series, quickly garnered lasting popularity. Addams himself was a talented and funny man who did his best to live up to a reputation for grotesquery and outrageousness.
A good selection of cartoons from one of his books, Monster Rally, is up at the fantastic Golden Age Comic Book Stories, from where I stole these three fine, characteristic cartoons. (Click for readable versions.)
Addams also designed a number of book covers, which is where we come in. As well as the covers for his own books...
..he also did a number of cover designs for similarly-minded writers.
I would love to see an edition of Waugh's The Loved One ilustrated by Addams throughout. If any artist was to find death no barrier to producing new work, it would surely be Addams.
Regarding that Ray Bradbury book, above, an interesting bit of trivia. Originally, Addams and Bradbury were going to collaborate on an imaginary family history about a clan of gothic monstosities: the 'Elliott Family'. The project never got off the ground, but Bradbury went on to write about the Elliots in From the Dust Returned (finally published in 2001 with an old Addams cover), while Addams preliminary sketches for the Elliots ended up morphing into the beginnings of his Addams Family characters.