Vigilante protagonist

Generally any "hero" protagonists who are not particularly welcome by the local law enforcers or even actively pursued as criminals despite the "good" they do, either because they have zero tolerance or even they are somehow corrupt and deserve a beat-down.

Vigilantes do not only protect the "weak" (usually a side product of their activities rather than the actual goal), but often achieve this by breaking the law in various ways, regularly going over the top in their methods to punish the wicked which garners their awfully common status as dangerous criminals (which they are, really).

Batman (in some continuities), The Punisher, etc. are some good examples.

Related:
* Hero protagonist
* Outlaw protagonist
* Revenge