It is not a real name. He is a narrator of the story. He’s a type of the guy who you exactly don’t want to meet, especially, in an underground catacomb. This character is cold and ruthless killer. He does not enjoy killing but also thinks that it’s necessary. While reading, we feel what an unreliable and unsympathetic person he is. Also, he was doubtful because during the whole text we still didn’t get his thoughts – is he confessing to committing murder or bragging about it?
Montresor in the Essays