It isn't difficult to see why James Bond stands as Hollywood's third most successful franchise: exotic locations, gadgets, fistfights, explosions... Weighed sorely on its escapism value alone, the Bond franchise towers above the competition. It's what has made this series so appealing to the masses - and for so long.
But not all spy films are quite so concerned with opulence and grandeur. The spy film is deeply tied to a notably bleak and paranoid part of real history: the Cold War. Here was a time where double agents, murder, and betrayal ran rampant, and filmmakers have been keen to explore the era - and its effects on the globe - for decades ever since.
In the best spy films - be they bleak or stylish - the same question always seems to crop up: what exactly, is a spy? Perhaps the most interesting interpretation can be glimpsed in novel The Spy Who Came in From the Cold, in which the lead protagonist derides those working the profession as "a bunch of seedy, squalid bastards like me …civil servants playing cowboys and Indians to brighten up their rotten little lives."
That's one take on it, but cinema has offered up countless interpretations of "the spy," leaving audiences to ponder the ethics for themselves. Here are the 20 best in the genre - and for the sake of variety, it's one film per franchise, to avoid a totally Bond-centric list...