Mike Ehrmantraut – Breaking Bad
Mike never really fit the cliché of a TV villain, but it was his low-key savageness that made him so dangerous. Brought in to be a fixer, Mike handled business unlike anybody else could. That’s part of the reason Walter White had to enlist his help in the first place.
As we learn later, Mike’s discharge from the police department was an act of selflessness, and his involvement with the Albuquerque mob was just a consequence of some things that were totally out of his control. As the right hand man to Gus Fring, Mike was forced to do a lot of unseemly things, but he performed his duties better than anybody could.
When he got involved with Walt and Jesse, he was also a very competent and reliable ally. He formed a deep connection with Jesse and he constantly tried to steer him in the right direction. He acted as a mentor to the younger drug dealer, and as Walt devolved into the ruthless killer he eventually became, Mike became the mentor and father-figure Jesse needed.
Mike met a very unkind end, thanks to the awful Walt, thus cementing his place as a bad guy turned good. Seeing his love and respect for a young man in need makes it really hard to be mad at him.