Dr. Kenzo Tenma – The main protagonist of the series. A japanese neurosurgeon working at Eisler memorial hospital in Dusseldorf, Germany. Tenma’s surgical skill becomes evident to his superiors at the beginning of Monster. He is engaged with the hospital directors daughter in the beginning of the anime and has a bright future ahead of him but it all changes when he goes against the orders of the hospital director and saves the life of a young boy with a gunshot wound on his head. This course of action alters his life forever.
Johann Leibert – The boy Dr. Tenma saves. Johann Leibert is the “Monster” of the title and principal antagonist of the series, not much is known about his past. He is referred to as the new Hitler by many politicians in Germany, He is treated like some kind of God by criminals, a hero to children and to others a monster with seven heads. He is highly intelligent, charismatic, manipulative able to sway people to his will just by using words. He isnt seen that much in the entirety of the series but he orchestrates the events that happen from the shadows. You need to watch this anime to see how cool this character is. Im doing such a poor job of describing how cool he is.
Nina Fortner/Anna Leibert – Johanns twin sister. A sweet, kind, loving, hardworking and intelligent young woman. She seems to have a happy life but she discovers there are parts of here past she cant remember.
Inspector Lunge – Is cool as hell. Inspector Lunge is a BKA detective assigned to the murder case that happened at Eisler memorial hospital. Lunge has an excellent memory, he claims to have a memory chip inside his head, he enters and accesses data by making typing gestures with his hand. He seems devoid of emotion, which allows him to commit himself to every case on which he works and at the same time completely ignore his family. He thinks Tenma as the prime suspect and believes that Tenma just made Johan up. He sees Tenma as a fascinating killer and chases him for almost the entire series.
Eva Heinemann – The daughter of the director of Eisler Memorial Hospital Tenma’s fiance, she is independent, superficial, bossy, demanding and manipulative. She also hates not having her way. She later leaves Tenma after being demoted of his postion after he disobeys her fathers command to save the life of a mayor a choice she would later regret.
Deiter – A young boy who Tenma saves from a man named Hartmann after discovering that he was being physically abused. Deiter follows Tenma throughout his journey to find Johan. Deiter also shows an interest in soccer.