Victor Frankenstein builds the creature in his laboratory through an ambiguously described scientific method consisting of chemistry (from his time as a student at University of Ingolstadt) and alchemy (largely based on the writings of Paracelsus, Albertus Magnus, and Cornelius Agrippa). The creature horrifies Frankenstein, and the scientist immediately disavows the experiment. Abandoned, frightened, and completely unaware of his own identity, the monster wanders through the wilderness searching for kindness and acceptance.
He finds brief solace in a woodshed beside a remote cottage inhabited by a family of peasants, the DeLaceys. Eavesdropping on the family's conversation, the creature familiarizes himself with their lives and comes to regard them as his own family, referring to them as his 'protectors'. He learns to speak by listening to the family teach French, their native language, to an Arabian daughter-in-law, and the creature becomes eloquent, educated, and well-mannered in a short time.
After much deliberation about revealing himself to the family, the creature introduces himself to the patriarch, the blind father, and who accepts him into his home and treats him with kindess. The blind man cannot see the creature's "accursed ugliness" and considers him a friend. When the rest of the family returns, they are terrified of the creature and drive him away. Still hopeful but bewildered, the creature rescues a peasant girl from a river, but is shot in the shoulder by a man who claims her. Heartbroken and enraged, the creature renounces all humankind, swearing revenge on his creator for abandoning his grotesque creation to a cruel and intolerant world.
Meanwhile, Frankenstein exiled himself to the mountains to reconcile his grief and despair. The monster approaches him at the summit and insists Frankenstein hear his plight. The creature tells Frankenstein his story, while also pleading with his creator to manufacture a female equivalent to mitigate the loneliness of his existence. Frankenstein agrees, but, aghast at the possibility of creating a race of monsters, abandons the agreement preceding the female creature's completion and enraging the monster. Before fleeing into the night, the creature threatens Frankenstein saying, "I will be with you on your wedding night!"
Later, the creature kills Frankenstein's best friend, Henry Clerval, and his bride, Elizabeth Lavenza. Due to the incident, Frankenstein's father dies of grief. Frankenstein then dedicates his life to hunting and destroying the product of his experiments. Searching for the creature in the Arctic Circle, the scientist loses control of his dogsled and falls into the freezing water, contracting severe pneumonia. A ship exploring the region rescues Victor. Before succumbing to his illness and dying, he relates his entire story about the creature and his experiment to the captain, Robert Walton. Later, the creature boards the ship, intent on taking his final revenge, but, upon finding his creator dead, is overcome with grief. The monster pledges to travel to "the Northernmost extremity of the globe"; he leaps from the boat and disappears.
Frankenstein's monster is by no means an evil being, as is often misconceived. He is a timid, emotional creature who is only driven to commit acts of violence out of despair and anger. All he wanted in life was to share his existence with another like himself, to find a sense of belonging in a world filled with people that feared and hated him for being different from them.
Though many adaptations depict him to be an unintelligent brute, the monster is actually quite eloquent and articulate in the original Frankenstein book. He learns how to dress himself not long after his creation and learns to speak the French and German languages fluently by the time he is eleven months old. He is surprisingly spiritual and it was implied in the book that he was a vegetarian, preferring things like berries and nuts to meat.
- Frankenstein's monster is often classified as "undead", but this is not entirely accurate. While he is made from pieces of human cadavers, his constructed nature implies that he is actually a golem, albeit one made of flesh.
- Being created through a form of alchemy, Frankenstein's monster also qualifies as being a homunculus.