Who developed the first comprehensive theory of personality?

The answer is: Sigmund Freud

In His comprehensive theory of personality, he introduced several terms that he considered as parts of human's psyche, such as unconscious mind, psycho sexualstages, and defense mechanisms.

Unconscious mind refers to the feelings and urges that exist outside of our awareness, psychosexua; l stages refers to the development of sexual libido throughout human lives that correlated with their behavior. Defense mechanism refers to the efforts made by individual's mind in order to protect us from horrible/unacceptable emotion.