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. This can also include villains who commit copyright infringement, stealing another's work and passing it off as their own.

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.