We have recently seen a shift from the traditional idealistic hero toward what is touted as the antihero. Antiheroes are less moral, generally more ruthless, and less admirable.
Webster’s defines an “antihero” as “a protagonist or notable figure who is conspicuously lacking in heroic qualities.”
Deadpool, Arya Stark, and Malcolm Reynolds are all examples of less-than-moral people who we nonetheless love.
Still, the term “antihero” makes no sense to me.
In the end, all those examples I listed have their boundaries. They do go after those they see as guilty without remorse. They do inflict terrible atrocities on their enemies.
At the same time, they are almost always avenging or protecting the victims of their own victims. Then again, we have seen villains with codes, out for justifiable revenge as well.
This begs the question, when does a hero become an antihero and when does an antihero become a villain?
From my own observation, heroes and antiheroes tend to put doing the right thing first and do bad things as a side effect. The villain does bad things first and does good as a side effect.
This line becomes so murky, it can be hard to see straight. Arya Stark and Deadpool are both out for revenge and do inexcusable things as a result. But I have yet to see either called an outright villain.
Meanwhile, characters like the Lord Ruler of Mistborn have wholly reasonable, even humanitarian motivations, but no one doubts they are villains. The definition is fluid.
In the end, I believe the only difference between an antihero and a villain is how the reader feels about the character.
If you like her/him more than her/his victims, then you can say “antihero” instead of “villain.” If you like the victims more, then you say “villain.”