So maybe Dexter is showing us a new slant for anti-hero stuff.
Or The Equalizer or John Wick... both good examples that don't meet the original post's thesis criteria, but I think Dexter is by far the best example of killing (as a recurring plot point) done well because that show was so good, for so long, at having a "bad guy" serial killer as the main character, AND having him both relatable and sympathetic. As opposed to the stereotypical, basement dweller, Silence of the Lambs type.