What kind of villian is Montressor?

In The Cask of Amontillado, Montresor can be perceived as
both the antagonist, as well as the protagonist for various reasons. Montresor can be
seen as the antagonist because, quite simply, he murdered a man. However, he can also be
seen as the protagonist because to have killed Fortunato, he would have needed a motive,
which could be supported by the first line ("the thousand injuries of Fortunato I had
borne as I best could, but when he ventured upon insult, I vowed revenge.") Overall, it
probably makes more sense to give Montresor the title of the antagonist because,
although he did have an incentive, his reason was not strong enough for full on
annihilation.