Noun
negative Nancy (plural negative Nancies)
(derogatory, informal) A person who is considered excessively and disagreeably pessimistic.
Everyone has that inner voice, the one that's a Negative Nancy. I'd say to ignore that voice and to be confident and follow your heart. Katharine McPhee
Calypsocookie: I'm gonna be called a Negative Nancy but I've never understood the appeal of fireworks. Source: Internet