The Shock! phenomenon currently holds several mysteries as to who thought up the idea of the film package at Screen Gems, who developed the marketing plan for it and the choices made during that time regarding catalog design and even the name of the package of Universal films the company was preparing for television sale. I believe I may have accidentally stumbled upon a couple of answers. The genius or geniuses behind Shock! are still unknown, but it appears that the 1946 film SHOCK, with Vincent Price and Lynn Bari, may have generated the idea for the title of the package AND a significant part of the design of the Shock! catalog.
Take a look at the cover of the Screen Gems catalog:
And then a poster for the SHOCK film:
Clearly, the font selection for the Screen Gems' catalog mimics to a substantial degree the font and color of font that had been designed for the film's poster, as well as the prominent placement of the upper face of a person above the "Shock" title. It is not a long stretch to deduce that Screen Gems also borrowed the film's title as an effective, bold pronouncement for their own catalog of Universal horror and mystery films.
Two Heads Are Better Than None! - Vincent Price with the decapitated head of Peter Lorre from "Tales of Terror".
4 hours ago