the characters in the movie are the same in the book. both the book and the movie are about the corleone crime family. vito corleone serves as the crime boss. vito corleone and the other characters are not based on real-life people. however, some characters connect to real-life mobsters. these include the real "five families" in new york. real-life mobsters like frank costello and carlo gambino were a basis for vito corleone. johnny fontane is based on frank sinatra.