Most Helpful Guy
* Definitely check out Natural Born Killers as Regulatus mentioned.
* True Romance.
* Bonnie and Clyde (1967) and the 2013 Bonnie and Clyde TV miniseries.
* I haven't seen them, but Honeymoon Killers (1969), Deep Crimson (1996), Lonely Hearts (2006), and Alleluia (2014), are supposedly inspired by a a real criminal couple who targeted people in personal ads and received the death penalty.
* The diner scene that starts and ends Pulp Fiction also comes to mind.