A Thief is a type of criminal that is found in almost all media. They are most known for stealing stuff. Each thief can range from petty to extreme (depending on what item they steal). Most thieves steal for money or jewels, but there are some thieves who do it for the thrill.
There are also a small percentage of thieves that literally cannot help themselves, having a psychological disorder known as kleptomania, which causes them to compulsively steal.