Professional wrestlers often take ring names to hide their identities or to play a character more effectively. Professional wrestling, such as the WWE, is about putting on a show as much as it is about having an actual wrestling match. Wrestlers with memorable ring names stay in the audience's mind.
Another reason for ring names is that the wrestling company often makes its performers take them to make the name easier to trademark. One of the most famous wrestlers is the Undertaker, whose real name is Mark Calaway. The Undertaker has undergone many gimmick changes over the years, but mostly plays a supernatural zombie-like character.