How is this possible?
Two reasons spring to mind.a) It's a derived work, and Mr. Sparrow (aka. Johnny Depp) don't mind other people making money off his likeness.
b) They're breaking the law.
My question is that if you have drawn\painted a portrait yourself of somebody famous is it legal to sell it or are you asking for trouble?
It depends on whether they've been dead for x years (and thus the copyright for their likeness has expired). So yourself and Abraham Lincoln, okay - yourself and Angelina Jolie, not so much. That's why movies have that seemingly stupid disclaimer at the bottom stating the events and characters are fictional and any likeness of real people is "coincidental". They do this even for films that are "based on a true story".