A narcissist is someone who exhibits Narcissism, characterized by an excessive focus on themselves, a need for admiration, and a lack of empathy for others. This personality trait can manifest in behaviors such as seeking constant validation, displaying arrogance, and having difficulty maintaining healthy relationships. Narcissism exists on a spectrum, and in more severe cases, it can be classified as Narcissistic Personality Disorder (NPD), which can significantly impact an individual's personal and professional life.