Dillinger's main problem wasn't that he was a trigger-happy psycho (although one could certainly make the argument), it was that he took his girlfriend to the movies. After eluding the FBI over the course of several expert robberies (bank and otherwise), he gets gunned down because his girlfriend turned him over to the cops.
Gruesome, "Dick Tracy Meets Gruesome"
Many of the problems that can happen during bank robberies happen because there are too many people moving around trying escape or alert the authorities. Gruesome, played by all-time-great movie villain Boris Karloff, has devised a pretty clever solution to this: A gas that causes everyone who is exposed to it to freeze in their tracks. They unleash the gas, empty out the vault, and get out of there.
They, "They Live By Night"
The bank robbers in "They Live By Night" are some of the best in movies because of the wide range of personality dynamics at play: You've got everyone from a wide-eyed innocent, in love and itching to get out of the bank robbery game for good, to the killer psychopath. Diversity is important, don't forget that.
Thomas Crown, "The Thomas Crown Affair"
Bank robbing is kind of like dating – it helps if you don't really need what it is that you're trying to get. So it stands to reason that the millionaire businessman and bank robbing hobbyist Thomas Crown (played by Steve McQueen and Pierce Brosnan in the remake) is one of the best bank robbers of all time. He doesn't need the money, he's just bored.
Virgil Starkwell, "Take The Money and Run"
Of course, some movie bank robbers are valuable because they show hopefuls how NOT to rob a bank. That argument could be made for Virgil here, played by Woody Allen in one of his funniest comedies. His most famous mistake is when he attempts to rob a bank via a handwritten note – but the teller can't make out whether it says "gun" or "gub." You might not think penmanship is important in bank robbing, but it totally is.
Sonny & Sal, "Dog Day Afternoon"
And speaking of inept bank robbers – what discussion on the subject would be complete without "Dog Day Afternoon"? The mistakes Al Pacino and John Cazale make in this movie are countless, so let's start with the most obvious: Make sure there's money in the bank when you go to rob it.
The Ex-Presidents, "Point Break"
One important thing to remember when you're starting a gang of bank robbers is to have a good theme. This distracts the eye from more identifying features, and it's just a cool thing to have. The gang of surfers/bank robbers headed up by Patrick Swayze put on weirdly creepy masks of various former presidents. Which, like we said, is creepy. But also kind of cool.
Neil McCauley, "Heat"
Robert De Niro's character in "Heat" is defined by his simple philosophy towards a life of crime: "Don't let yourself get attached to anything you are not willing to walk out on in 30 seconds flat if you feel the heat around the corner." And he takes this mantra to heart, which makes him a great bank robber and a terrible bowling league partner.
The Joker, "The Dark Knight"
When you're a murderous psychotic whose only pastime is setting things on fire and blowing things up, one thing you can do to surprise people is pull of a brilliantly orchestrated bank heist. The Joker does just that in the opening sequence of "The Dark Knight," in which he not only depends on his underlings' succumbing to the temptation to murder each other for the loot, but escaping as part of a school field trip in a school bus.