Naysayer
A naysayer can be referred to someone who always has something negative to say about something, or they have doubts on the possibility of success. They always tend to focus on the obstacles rather than the potential. It refers to a person who always expresses negative opinions or doubts. Naysayers are like the party poopers who always bring the mood down. They try to find fault in every situation and they act cynical and often oppose and refuse to things.