Nomenist

A person who judges someone based upon their name, regardless of other factors.

Beth: "Susie! I met this great guy! He's cute, funny, sensitive-"
Susie: "Wow, he sounds perfect! What's his name?"
Beth: "Garrett."
Susie: "Oh. Whoa, you shouldn't be around this guy, Beth: Garretts are bad news. I knew a Garrett once, and he-"
Beth: "Oh, cut it out, Susie. You're such a nomenist."