Anybody that hates on other people just because they have a different opinion on certain aspect of a video game. These people tend to be arrogant and ignorant people.\

These people, like plunderfull mentioned, would dislike a sequel of a certain game and like the old one. Also, they will attempt to make the sequel of the previous game exactly like the previous game. They degrade anyone who does likes the regular version of the sequel and dislikes the revised version of the sequel which is the same to the game before the sequel.
There are lots of threetards all over the internet.

A few threetards in the Bnet forums are:

Southpole, Kira Onime, eRage Sanctity, St3althsniper22, Sentox 6.
by The 1337 Truth November 13, 2011
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a person who accessorizes his or her Chrysler 300
The threetard put a Bentley grill on his Chrysler.
by mme_evil_ninja August 1, 2009
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