Goodfellas (1990, Warner Bros., dir. Martin Scorsese) is a famous cult classic now about some friends working their way up the Mafia hierarchy. With Robert Di Niro and Ray Liotta.
But it is the opening scene that is shocking, where the protagonist approaches and opens the trunk of a Buick, slashes and stabs and the shoots the occupant, blowing off the head, and announces "As far as I can remember, I've always wanted to be a gangster".
Note above the gangster psychology analysis in the murder of Billy Batts.