Ideas For Arcade Villains

So they added some new arcade heroes to the arcade set, but there are still only 2 villains. On the roster in the blitzcrank vs riven wallpaper, it suggested only 1 more hero and 3 more villains, which leads one to believe that there would be more villains. Does anybody have any ideas on which champs would be good arcade villains? So far I thought Karthus, Urgot, and Zed would be pretty cool.