Some wikis have very strong personalities.  Sometimes these personalities take over the site and identify with it. On occasion, this identification is so strong that it is hard to tell where the person stops and the site begins; and the media identifies this character as the wiki itself also.

This article is amusing: http://uncyclopedia.org/wiki/Wiki_Dominatrix

Although very tongue in cheek, it does partly describe what such a domineering character behaves like.

It is less a worry, however, how this person behaves. It is how the rest of those on the wiki react that matters most.  If they go along with making the king or queen of the wiki and butter up this person, an ogre of undesirable proportions begins to grow. Like Medusa, this person's whims affect the entire site and cause users to take sides, disappear or believe the most ridiculous things about the powers of this person.

If your wiki is growing a little king or queen, he or she must be dethroned quickly. Do it neatly, politely but effectively. Inform the would-be regent that your wiki is not a place for strutting, crowing, glowing or hogging it all. Your wiki is everybody's and he or she has no place without accepting this.