Adrian Leverkühn
This character is a painfully stricken philosopher. His young life is shaped by intensity, secrecy, and curiosity. Through his education, Adrian is brought into community with important people who shape the flow of his life. He falls in love with the humanities, becoming a musician and a philosopher. Adrian struggles to find a place to call home, and his life turns into a lengthy pilgrimage that takes him into new relationships. After contracting syphilis, he is unable to find treatment and slowly succumbs to madness as the disease warps his experience of reality.
Serenus Zeitblom
This is the narrator of the novel. His insight is helpful because he often intersperses commentary about young Adrian. They met once upon a time, but Leverkühn was always here today and gone tomorrow, so Zeitblom has assembled the story from what he could learn about the young philosopher. They shared time together in school. Also, sometimes the narrator inserts essays about the changing nation of Germany.
Wendell Kretzschmar
This musical teacher has a profound effect on young Adrian, pushing him toward the performance arts with this beautiful musical performances and lectures. The lectures are often fragmented and difficult to understand because Kretzschmar struggles with a severe speech impediment. His stutter and music combine to show Adrian that music is a kind of communication that can be resorted to when words will no longer suffice. Adrian oscillates between music and words, struggling to express his point of view.
Professor Shlepfus
This religion and philosophy teacher is a mystic at heart, but his instruction is met with some hesitation. For instance, he teaches that there is legitimate magic on the earth which has been documented throughout history by the alchemists, wizards, and mystics. He also explains that the secret to understanding magic is to understand the constant interplay between the spiritual realm and the visible reality experienced by waking consciousness. He believes demons are constantly influencing one's perception.
Schieldknapp
Schieldknapp is a poet and translator. He is an immediate friend of Adrian who sympathizes with his desire to capture language and translate meanings well. Together, they travel some, to Munich where they rent a room, and then on to Palestrina. Their summer there is eventful but difficult, as Leverkühn struggles to perfect his opera. Schieldknapp is one of the few people who sees Adrian's musical genius and encourages him to write.
The devil
In Leipzig, Adrian suspects that he is being led to his hotel, but instead, his guide brings him to a brothel. There he encounters the femme fatale, a enchanting young prostitute with whom Adrian falls immediately in love. At first he rejects her, stunned by the rapid turn of events, but before long, he succumbs to his desire. She warns him that she has contracted syphilis, but he insists. They make love, and then months later, unable to find treatment, young Adrian begins writing in his notebook that he has been contacted by Satan, the devil, who has instructed him on how he ought to live the remainder of his life. Satan tells the young man that by accepting the illness of the young prostitute, he has sold his soul to hell, and now will live for demonic purposes before being "called home," in time.
Leverkühn's nephew
For a brief episode, Adrian is able to see some hope in life. His family reaches out to him on his travels and they explain that his nephew is in some trouble. The young lad needs an adult to watch over him and keep him company after some unfortunate fate befalls the boy's parents. Leverkühn accepts and quickly realizes that his contact with a child brings back his own memories of young life. The encounter is deeply loving and familial, but before long, the boy dies and Leverkühn begins his descent into madness and death.
