The Vesper is the celebrated cocktail invented by James Bond in Casino Royale.  The superspy with the license to kill directs a bartender with exactitude: 

"A dry martini," [Bond] said. "One. In a deep champagne goblet."
"Oui, monsieur."
"Just a moment. Three measures of Gordon's, one of vodka, half a measure of Kina Lillet. Shake it very well until it's ice-cold, then add a large thin slice of lemon peel. Got it?"
"Certainly, monsieur." The barman seemed pleased with the idea.
"Gosh, that's certainly a drink," said Leiter.
Bond laughed. "When I'm...er...concentrating," he explained, "I never have more than one drink before dinner. But I do like that one to be large and very strong and very cold and very well-made. I hate small portions of anything, particularly when they taste bad. This drink's my own invention. I'm going to patent it when I can think of a good name."

-Ian Fleming, Casino Royale, Chapter 7, "Rouge et Noir'

It's obvious that the cocktail owes something to its literary roots. According to Wikipedia, the Vesper was created for Fleming by a friend to celebrate Bond.

Looking at the recipe, we see: 

• Russian Vodka and British Gin
• The components are famously shaken, not stirred
• Kina Lillet to add a bitter note to the herby Vermouth

It sounds like the sort of thing you might come up with to commemorate a cold-war superspy. It's a literary construct to celebrate the sex-and-death world of the British spy and his Soviet rivals. Well, that's my theory.

For more on actually mixing one of these, see this entry and its comments.  For more on shaking your cocktail, see Shaking and Stirring in The Foodie Pilgrim Cocktail Lab.