If we're letting Walt in, there's a huge list of morally ambiguous characters like Walt who we may as well let into the contest. Lelouch, Cartman, Catman, Jaime Lannister and Omar Little for example. It kinda ruins the credibility of a villians contest if we have characters who are not villains, but who do villainous things if needed.
I might not be saying the same thing after Season 5, but at the moment Walt should most definitely not be allowed into the list.
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if a tree falls in the forest and no one is around to hear it do the other trees laugh?