Taxi Driver (1976)

Suffering from insomnia, disturbed loner Travis Bickle (Robert De Niro) takes a job as New York City cabbie, haunting the streets nightly, growing increasingly detached from reality as he dreams of cleaning up the filthy city.

The Departed (2006)

South Boston cop Billy Costigan (Leonardo DiCaprio) goes under cover to infiltrate the organization of gangland chief Frank Costello (Jack Nicholson). This film is high up on my list of favorite films and Scorsese films for a number of reasons. From the cast, acting, and plot, it takes the cake in every corner. Read what Jim Emerson had to say on Roger Ebert.com