Forum Troll
From AmtWiki
What they are
A forum troll, is one who makes random useless posts on a forum, spouting generally inane drivel in an attempt to gain attention or personal amusement. In most cases nothing productive, helpful or generally useful is posted. It is common practice for such trolls to sit around pressing the refresh button and watching and waiting for a response.
Known Trolls
What to do about it
It is common practice to flame said trolls or simply to ignore them. While this works for some, a group has formed to stop the invasion of trolls, the call themselves Troll Hunters.