Villain Sue

Mary Sue is hardly limited to always being a goody two-shoes. The Villain Sue decided to take the dark and evil path, kicking a few dogs and probably cackling about it in the process. Whatever they are doing, they absolutely love to be evil.
This character pretty much shows up as an author's wish fulfillment to just be evil. Alternatively, in fanfiction, it might show up because the author favors the villain and wants a vicarious relationship with them. It might be a consequence of the idea that being evil is cool, taken to the logical extreme. Or, perhaps, the author just has a distaste for some (or all) of the protagonists and created the character to facilitate a Hate or Revenge Fic. Either way, the same author favoritism and plot bias are now working for the forces of evil. It may also come about as an attempt to create a Magnificent Bastard or similar style of villain, only to go too far and become one of these.
As far as overlaps go, there are two major ones. Sympathetic Sue is an easy one where the intent is to show that the character just had a crappy enough life to be forced into villainy. With this overlap, they are more of a Villain Protagonist than an antagonist in most cases. Tends to show up most often in fanfiction. The other common overlap is the God Mode Sue, with a ridiculous power level, forcing the heroes to act like morons, and/or requiring Deus ex Machina in order for the protagonists to stand a chance of defeating them. This is the type that generally shows up in canon. It can overlap with other types, such as Jerk Sue.
Probably the rarest type of Sue, as Villains are always given great powers and abilities to make their inevitable downfall more sweet. A true Villain Sue will probably never have one.
Category:Sue and Stu Classifications