Frankenstein is presented as a frame tale, told by Captain Walton while on an expedition to the North Pole, where he finds Frankenstein. Frankenstein is a scientist who created a monstrous human-like Creature. The Creature tried to explain his murders to Frankenstein, claiming that people rejected and feared him, begging Frankenstein to make him a mate. Frankenstein first agrees then destroys the mate. The enraged Creature kills Frankenstein's wife, fleeing to the North Pole. After Frankenstein dies, Walton sees the Creature mourning as he floats away on a raft.
The protagonist and main narrator of the story, Victor becomes interested in alchemy at a young age. In Ingoldstadt where he attends university, he finds that he enjoys chemistry and pursues it as a way of unraveling nature's secrets. He becomes a celebrated scientist there and discovers the secret to creating life. He makes a creature out of human body parts, yet when the creature comes to life Victor flees because his creature is too horrible. He suffers from great anxiety, and returns to his home only to encounter death and misfortune. He realizes that his own monster is causing great tragedy and Victor spends the rest of his life chasing his creation, obsessed with his intention to destroy it.
The hideous and giant creation of Victor Frankenstein, the monster is bright and sensitive. He encounters only rejection and ridicule from both his creator and society in general. His one wish is to have a female companion, and he asks his creator to provide him with one. Victor tells the monster he will, and then breaks his promise. Being despised by all who see him, the monster becomes bitter and violent, and sets out to ruin his creator's life.
As a small orphan girl, Elizabeth is adopted by the Frankenstein family and enjoys a harmonious upbringing alongside Victor. Described as angelic, sweet and passive, she consistently brings joy and comfort to Victor and his family. Elizabeth endures a great deal of grief when first Victor's mother dies, then William is murdered, and when Justine is wrongly convicted of William's murder and is put to death. She takes the place of Victor's mother after his mother's death, as the central maternal figure in the novel. She is betrothed to Victor and then murdered by the monster on their wedding night.
Victor's childhood best male friend, Clerval nurses Victor back to health when Victor falls severely ill after watching his creation come to life. Romantic and chivalrous, Clerval is interested in the humanities, and studies languages at Ingoldstadt, the same university that Victor attended. Victor keeps his monster a secret from Clerval. The monster kills Clerval to punish Victor for not creating a female companion for the monster.
Victor's kind and sympathetic father, Alphonse encourages Victor to find peace and comfort in his family. He adored his wife, Caroline, having taken her under his protection when her father died, and she had been poor and alone. After the murder of his youngest son, William, Alphonse gradually becomes more ill. He never ceases to support Victor and want for Victor to be happy.
Victor's extremely compassionate mother, she insists on bringing aid to poor families, and she is the one who adopts Elizabeth. Having struggled to make ends meet when her own father was ill, and then having been left penniless by her father when he died, she feels a great empathy towards the poor. She regards it as her duty to help those in need. Caroline is the archetypical Madonna figure: purely good, selfless, giving, loved and revered by all. She dies when Victor is 17 years old and Elizabeth takes on her role as the central maternal figure in the family.
Victor's beloved youngest brother, William is sweet and cherubic. The monster murders William by strangling him outside the Frankenstein home in Geneva. The monster commits the murder to punish Victor for leaving him. This action creates agonizing guilt in Victor for having created the monster, and it begins a tragic future for the Frankenstein family. The family's servant, Justine Moritz is blamed for William's murder and put to death.
Justine is taken into the Frankenstein family as their servant by Caroline, Victor's mother. Quiet and happy, she adores Caroline and attempts to imitate Caroline's every mannerism. Caroline treats Justine respectfully and even provides her with an education. When William is murdered, Justine is unfairly blamed and, in martyr fashion, faces her death penalty with dignity and resignation. Victor knows she is innocent but is powerless to change her sentence and her death increases his sense of guilt.
A family of peasants consisting of M. DeLacey, who is a blind old man, his son Felix, his daughter Agatha, and a foreign woman named Safie. They have been exiled from France for treason against their government. The monster observes them and learns from them how to speak. He tries to interact with them, but they are horrified by him, beat him and chase him away.
Victor's professor of chemistry at Ingoldstadt, Waldman encourages Victor's interest in science. He becomes a mentor to Victor, showing him how to use laboratory instruments and giving him advice. He shares Victor's desire to use science as a way of figuring out the secrets and mysteries of nature.
An Arctic explorer hoping to discover uncharted territory, his letters to his sister Margaret Saville in England frame the story in the beginning and end of the novel. He finds Victor, emaciated and ill, during Victor's pursuit of the monster on the ices of the Arctic. Walton rescues Victor from the elements and helps him to recover. During this time period, Victor tells Walton his story and Walton relates the story in his letters to his sister.