The entire allure of the espionage novel is to escape from your humdrum world and live vicariously through a suave badass as he kills bad guys and beds women. The storylines are spiced with a modicum of violence; however, for the most part, the reader is there to just to watch him work his magic.
The lead character has its origins in shady gumshoes from the likes of Spillane and from film noir private dicks. They are every bit the anti-heroes - their ultimate aim is to do good; however, their humanity often gets in the way. Whether it's sexual urges or just arrogance (I'm talkin' to you, Bond!), things often get complicated in their pursuit for truth and justice.
Naturally, when a convention of the genre happens to be shagging hotties, you're going to get some wonderfully risque cover art. These covers make it abundantly clear: this is not a stuffy Hercule Poirot mystery - there's going to be a generous helping of sex involved. Miss Marple would not be pleased.
So, here's a few covers from the late sixties and seventies. By this time, paperbacks had largely moved away from the beautifully painted pulps that we are all probably familiar with, and moved on to poorly conceived photographs. They're not nearly as good a quality, but still a part of the history of espionage/action fiction nonetheless. Enjoy.
Note: Last 9 images taken from a Flickr photoset