A person who, on a message forum of some type, attacks and flames other members of the forum for any of a number of reasons. A real troll usually flames threads without staying on topic, unlike a "Flamer" who flames a thread because he/she disagrees with the content of the thread.
Trolls are people who flame the posters themselves, they flame because of rank, previous disagreements, sex, status, etc...
Trolls MUST NOT be confused with Flamers, who attack threads based on their content or lack thereof.
inuyasha8497493745: "I like to watch InuYasha because it's a great show."
troller: "You suck newbie! Why don't you just shut your damned mouth!?!"
Flamer: "InuYasha sucks... the anime is poorly drawn, etc...."