Paul T. Costa is a prominent American psychologist known for his work in personality psychology. He is best recognized for developing the Five Factor Model of personality, which outlines five key traits: openness, conscientiousness, extraversion, agreeableness, and neuroticism. This model has significantly influenced both research and practical applications in psychology. Costa has collaborated extensively with other researchers, including Robert R. McCrae, to explore the implications of personality traits on various aspects of life, such as mental health and behavior. His contributions have helped shape our understanding of how personality influences individual differences and interpersonal relationships.