Here's an actual flag used by a famous pirate named Calico Jack.
The flag is said to be that of Thomas Tew (also known as the Rhode Island Pirate) who first set sail across the high seas in 1692.
I'm sure you've heard of the infamous Blackbeard, this was the flag that flew on his ships mast.
This flag was flown from Henry Every (or Avery)'s fearsome pirate ship for many years before his retirement.
Here's a small, animated pirate flag with skull and crossbones.
This one is a bit old and tattered, but it's a bit different from the rest so I'm putting it here in case someone wants this animation.
This animated flag is pretty similar to the one flown by Calico Jack.
Last Jolly Roger for now, a typical skull and cross-bone flag (complete with eye patch).