Gin, vodka, and Lillet Blanc — James Bond's cocktail from Casino Royale, 1953. Stir for better results.
The Vesper Martini was created by Ian Fleming for his 1953 novel Casino Royale, the first James Bond novel. Bond orders it at the casino bar: '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.' He names it after Vesper Lynd, the female protagonist.
Fleming specified Kina Lillet, a quinine-containing French aperitif wine that was discontinued in 1986. Lillet Blanc (its replacement) has less quinine and is somewhat sweeter — Cocchi Americano is a closer substitute in terms of bitterness. Bond's famous 'shaken, not stirred' instruction is technically wrong: spirits-only cocktails are always better stirred (clearer, silkier, less aerated). But it's fiction.
Replace Lillet Blanc with Cocchi Americano for a more bitter, quinine-forward result closer to Fleming's original Kina Lillet.
Replace Lillet Blanc with a dry white vermouth (Dolin Dry or Noilly Prat). A more standard dry martini with vodka added.
Reduce gin to 2 oz and add a teaspoon of freshly squeezed grapefruit juice. Slightly more citrusy and approachable.