Is it possible to open a locked door with a credit card, or is it just a device used...

[Citizen DeCat]

...in TV and movies? Given the complexity of modern locks, I find it hard to believe.

 

[Tyler]

You're correct, most modern locks make this feat impossible. With older locks though this is entirely possible, and actually quite easy. I've seen it done on a couple different occasions.

http://www.wikihow.com/Open-a-Door-with-a-Credit-Card