To be honest no one is “Evil” everybody is doing in what they believe in. We can call Eren and the entire scouts evil for killing once that were human titans but they have a reason for doing so. Titans can be the good guys they just have no control of themselves. Anyone can be considered the “Evil” character based on perspective and what or who you want to believe. Bit if i would call someone an evil character it would be kenny. He brutaly kills people be he passed. But he had his own intentions and own backstory but to me he seems the most murderouse one.