If you were a reader of the early FAMOUS MONSTERS magazines, the back pages would introduce you to a wondrous assortment of monster goodies available through the "Captain Company," located in Philadelphia. Aurora models, 8mm horror films, posters, and more were available for mail order. One of the most seductive offerings was for horror paperbacks, which were published with an envious frequency in those days from companies like Belmont, Ace and, perhaps the biggest publisher of the lot, Ballantine. The Ballantine horror series is memorable for not only being offered via FM's Captain Company, but for its covers, chiefly done by Richard Powers. It's difficult to describe Powers' style, but it was clearly a then modern take on horror illustration, one that abandoned traditional gothic elements to focus on weird design that was near abstract, and at times completely so.
Here is an example:
This is probably not a Powers cover, but this will give you another sense of the modernistic design of the Ballantine series:
The following will be an updated list of these Ballantine horror paperbacks, which some online websites call Ballantine's "Chamber of Horrors" series, a term I've seen used in a FAMOUS MONSTERS ad, but one that I've yet to see in a Ballantine paperback. I'm using old FAMOUS MONSTERS magazines, the actual paperbacks, and some online hunting to generate this list.
THE GRAVEYARD READER (1958, BB 257) - ed. Groff Conklin. Twelve stories and introduction.
DEALS WITH THE DEVIL (1959, BB 326) - ed. Basil Davenport
TALES TO BE TOLD IN THE DARK (1960, BB 380) - ed. Basil Davenport
INVISIBLE MEN (1960, BB 401) - ed. Basil Davenport
ZACHERLEY'S VULTURE STEW (1960, BB 417) - ed. Zacherley
THE DOLL MAKER (1960) - Sarban
SOME OF YOUR BLOOD (1961) - Theodore Sturgeon
THE OTHER PASSENGER (1961, BB 480) - John Keir Cross. Short stories.
THINGS WITH CLAWS (1961) - ed. Whit & Hallie Burnett
ZACHERLEY'S MIDNIGHT SNACKS (1961) - ed. Zacherley
NIGHTS BLACK AGENTS (June 1961, BB 508) - Fritz Leiber
TALES OF LOVE AND HORROR (1961, BB 522) - Don Congdon
THE CLOCK STRIKES 12 (1961, BB 531) - H. R. Wakefield
SARDONICUS (1961, BB 540) - Ray Russell
NOT LONG FOR THIS WORLD (1961, BB 542) - August Derleth
ALONE BY NIGHT (1961, BB 563) - Michael & Don Congdon
RINGSTONES (1961) - Sarban
NINE HORRORS (1962) - Joseph Payne Brennan
SURVIVOR AND OTHERS (1962) - August Derleth, H.P. Lovecraft
SHADOWS WITH EYES (1962) - Fritz Leiber. Six short stories.