The Cheshire Cat
This one may seem like a stretch, but a lot of official merchandise lists him as a villain. Since Wonderland is already filled with some pretty chaotic characters, they just need a little push in the right direction. The Cat is an agent of the Friends who generally manipulates unsuspecting souls like Alice to get them in trouble, or generally lead them down the path of evil. He interferes with several trials The Queen of Hearts puts on. If the defendant is evil, the Friends get another soul; if they're good, there's one less good soul to interfere with the Friends' ultimate agenda. But in reality, the Cheshire Cat is really working for The High Council and only uses his Friends status to spy on the Queen of Hearts. His Wasteland counterpart, on the other paw...
His strange morality makes him a difficult ally, but his role as a double agent with the Friends is extremely useful, and his existence in one of the most chaotic centers of magic in all the worlds makes him an invaluable source of information. Although at times, he seems to enjoy his role pretending to be one of the Friends a little too much. No one is exactly sure who's playing who here...