Joe Carroll from The Following gets my vote.  He's completely demented and wicked.  (This is if you're going for someone who is seriously bad in the sense of being cool.)



If you're going for bad as in not getting anything accomplished, then you have the Moonintes:



And MC Pee Pants:

It's def Walt aka Heisenberg! Breaking Bad rocks! But, maybe Russell Eddington from True Blood too.

King Geoffrey from game of thrones

Marcus Alvarez President of the Mayans in Sons of Anarchy,he's not as bad or scary since the beef between the SOA and Mayans ended when het set his son up for a hit