Any person or zodiac can be a narcissist. In astrology, a sun sign can maybe help you to figure out the motivation to act vain. Aries maybe out of stubbornness, Taurus maybe protective, Gemini confused, and so on. Very often a person just hides insecurity with narcissism. Personally, Leos were for me always the most self-loathing, but they are also funny with it, and they can challenge you to think bigger.