Like Goodfellas, Casino was based on a non-fiction book by Nicholas Pileggi, and both of those films were co-scripted by Scorsese and Pileggi. All four of those films are dark, but I would say the darkest one is Casino. In particular we can point to what is now Scorsese’s tetralogy on the mafia, featuring in each case Robert De Niro in a pivotal role – Mean Streets (1973), Goodfellas (1990), Casino (1995), and The Irishman (2019).
Martin Scorsese has won fame for a variety of films, but his signature productions have been his films about mobster life.