A "prophet of doom/disaster" is someone who consistently predicts negative outcomes or events. In some instances, people may view these individuals as pessimistic or overly negative. If you're looking for alternative ways to describe this type of personality or attitude, other synonyms include "grim prophet," "catastrophe predictor," "pessimistic forecaster," "gloom and doom merchant," or "bad news bearer." Each of these terms conveys the prominent trait of consistently determining that the future will include a negative outcome or event. People who are referred to in this way may be viewed as having a habit of always anticipating the worst-case scenarios.