Gaston de Sainte-Croix (1904 – 1977) is one of many prolific illustrators of whom almost nothing is known beyond the work that bears their name. 

It's just possible that it's a pseudonym; it has been linked to other names of artists that we know are pen names, including Xavier Saint-Just and Georges Neczpal. 

It is said that he was a friend of the illustrator Rojan, although it is almost impossible in the world of erotic illustration not to know the great Rojankovski.

Sainte-Croix's main claim to fame lies in the more than three hundred cover illustrations he created for paperback science fiction titles between 1965 and 1973, mostly for the publisher Fleuve Noir. 

He was a master of SF art.

Long before his career in Futurist art, his colorful style appeared in the illustrations of some period classics, The Diary of a Chambermaid and Julie's Wanderings, Le Grand Meaulnes... then almost a decade later, he appears again as a creator of pencil drawings for the Nous deux editions.