The New York City Police Department is frequently featured in many movies simply because New York City is the setting for so many movies. But over the years there have been several movies in which the NYPD was the one of the main, if not "the" main character in the movie.
William (Bill "Hopalong Cassidy") Boyd in "The Cop" - filmed in NYC (1928)
Listed here are some movies in which the Department was the main theme of the movie as well as some movies that featured the NYPD in a lesser role or through props such as radio cars.
Titles with as asterisk - * - are movies with the NYPD as a main subject,
titles with a double asterisk - ** - are good for one or a few scenes only,
titles with a triple asterisk - *** - are also recommended as good movies.