Star Trek: Voyager (1995)

S3E18 Darkling

Stardate: 50693.2. In an effort to enhance his personality, the doctor decides to integrate the psychological traits of well-known historical figures. However, he soon becomes consumed by their more sinister aspects, leading to the emergence of a dual personality—one that is his usual self and another that is malevolent. Meanwhile, Kes expresses her desire to depart from Voyager as they encounter a civilization that possesses extensive knowledge about the unexplored area of space they are navigating.