An Internet troll, or simply troll in Internet slang, is someone who posts controversial and usually irrelevant or off-topic messages in an online community, such as an online discussion forum or chat room, with the intention of baiting other users into an emotional response or to generally disrupt normal on-topic discussion.
(http://www.salagir.com/gfx/troll-web.jpg)
That troll looks cute, though.