Who wrote I made him an offer he can't refuse?

The phrase "I made him an offer he can't refuse" is famously associated with the character Don Vito Corleone in Mario Puzo's novel "The Godfather," published in 1969. The line is also well-known from the film adaptation directed by Francis Ford Coppola. Puzo is credited with creating the original story and characters for both the novel and the screenplay.