Clarence Leiter was a British Secret Service agent working for Station S. He joined forces with James Bond to take down Le Chiffre. As a result of Leiter and Bond's efforts, Le Chiffre lost all of his money in a bacarrat game, and was subsequently killed by Bond.

Clarence Leiter appeared as Bond's primary ally in Casino Royale, making him the first of one of many such characters to appear on screen, and he was played by Michael Pate. He is combination of two characters from the novel, CIA agent Felix Leiter and Deuxieme Bureau agent Rene Mathis.