All four were mentioned above - Lorraine Bracco (Dr. Melfi), Michael Imperioli (Chris), Tony Sirico (Paullie Walnuts), and Vincent Pastore (Big Pussy, who like Luca Brasi, sleeps with the fishes).

Oddly enough, there are also four actors who have appeared in a "Godfather" film and "Goodfellas" - Robert DeNiro, Vito Antuofermo, Catherine Scorsese and Frank Sivero.