Stand-up comedians are a vocational group with unique characteristics: unlike most other entertainers with high creative abilities, they both invent and perform their own work, and audience feedback (laughter or derision) is instantaneous. In this study, the Big Five personality traits (NEOFFI-R) of 31 professional stand-up comedians were compared to those of nine amateur comedians, 10 humor writers and 400 college students. All four groups showed similar neuroticism levels. Professional stand-up comedians were similar to amateur stand-up comedians in most respects. However, compared to college students, professional and amateur stand-up comedians on average showed significantly higher openness, and lower conscientiousness, extraversion, and agreeableness. Compared to stand-up comedians, comedy writers showed higher openness, conscientiousness, extraversion, and agreeableness. These results challenge the stereotype of comedians as neurotic extraverts, and suggest a discrepancy between their stage persona and their true personality traits.