Victor Frankenstein, the creator of the creature who wants to determine the limits of human mortality.
The creature is a main character who asks Victor to create a mate for him, but his creator is appalled by his appearance and leaves the creature to fend for himself.
Henry Clerval is Victor's best friend who protects and comforts Victor, later killed by the creature.
Mr. De Lacey is a blind man who is the only character who isn't afraid of the creature.
Alphonse Frankenstein, Victor's father, serves to remind Victor of the outside world when Victor gets so caught up in his experiments.
William Frankenstein, Victor's brother, is also killed by the creature, and Victor allows someone else to take the blame.
Elizabeth Lavenza is adopted by the Frankensteins, but she and Victor fall in love and get married. She's killed on their wedding night.
Justine Moritz is also adopted by the Frankensteins. She's the one accused of William's murder, is sentenced to death, and then executed. Victor knows the creature killed his brother.
M. Waldman is Victor's professor who inspires him to conduct experiments, never thinking Victor would carry them so far.
Robert Walton is an Arctic explorer who finds Victor near death. Victor tells his story to Walton and wants him to risk his life and the lives of his crews to go after the creature and kill it.
You can get more detailed descriptions and the remainder of the characters by going to the link below.