Well, this is going to be controversial but I would say Eren from Shingeki no kyojin. I think everyone can give the meaning they want to that end of the anime or understand it as they prefer but for me everything he did and the change of personality with respect to his friends and acquaintances just with the excuse of "saving the world and humanity" seemed very worthy of a villain. He is a character with a very interesting arc and could always be debated.