Byronic Hero: Victor's dangerous experiments with science and very troubled past made him this. However, Victor's lack of compassion and responsibility for his Creation, who desperately longed for his love and affection, rather throws him off from being a redeemable character who is just misunderstood by society.
Cannot Spit It Out: Victor keeps the monster a secret, justifying this by saying that people wouldn't believe him anyway or call him mad. He still refuses to divulge the truth when Justine is tried for the monster's actions and eventually executed.
Determinator: Becomes totally obsessed with making his creature. It turns out badly. Later, he dedicates what is left of his life to tracking down and exacting revenge upon his creation.
Ditzy Genius: A deconstruction. He created sentient life while still in college but has no idea how to control his creation. His communication and decision-making skills also leave much to be desired. These facts together result in the deaths of many innocent people.
Final Speech: The majority (about 75%) of the book is Victor relating his back story to Walton, who transcribes the story into a letter to his sister. Victor talks an awful lot for someone about to die from being acutely weakened by coldness and exhaustion.
Foil: To his Creature. Unlike his Creature, Victor has family and friends who love him, lives comfortably in an upper class lifestyle, obtains a higher education, and has a tendency to isolate himself from the people who care for him. However, both Victor and the Creature are Byronic Heroes.
For Science!: Victor's initial motivation for the Monster's creation, though mixed with personal motives due to the recent death of his mother.
Freudian Excuse: The untimely death of Victor's mother coupled with Victor's fascination with the sciences probably inspired him to discover the mysteries of creation and make his Creature.
Herr Doctor: He is of Swiss descent (hence his German surname) and is obsessed with the mysteries of creation and discovering them through the sciences. However, Victor never receives his doctorate in the book.
Intelligence Equals Isolation: Victor cuts himself off from his family and friends while he's immersed in intellectual pursuits such as making his creature.
Jacob Marley Warning: Victor serves as a warning to Walton, who is in danger of becoming as obsessed with his exploration as Victor was with the science that led to the creation of his monster.
Kissing Cousins: With his adopted sister Elizabeth. It should be noted that they were blood related in the first publication of the novel in 1818. After her husband Percy Shelley's death, Mary changed this to non-blood related in the later publications, possibly for the novel to be accepted by a wider audience, as Mary was running into some financial troubles at this point.
Loners Are Freaks: He isolates himself from others when he's immersed in freakish pursuits, such as making his creature.
Miles to Go Before I Sleep: By the end of his narrative Victor is miserable enough to become a Death Seeker, but he promised himself and his dead family that he'd kill the monster first. Unfortunately for him the monster just happens to be really, really good at not being killed.
Nightmare Sequence: Has one immediately after he brings his Creature to life, involving Elizabeth's rotting corpse.
Poor Communication Kills: If Victor had told a few key people about the monster, a lot of trouble probably could have been avoided.
Punny Name: The name 'Victor' is actually a sneaky reference to Paradise Lost (a big influence on the story), as Milton often refers to God as 'the Victor'. And then, of course, the Monster equates himself with Adam...
Rousing Speech: He gives an epic one to the crew on Walton's boat near the end when he wants them to continue northward.
Sanity Slippage: Outside observers often comment upon Victor's haggard appearance after long periods of his isolation and tortured determination to a task, such as making his Creature or chasing his Creature across the world.
Smite Me, O Mighty Smiter!: Homeward bound from Ingolstadt, depressed Victor walks outside into a thunderstorm one night, and screams at the sky.
Stern Chase: After all of his family and friends are murdered, Victor ends up in a lengthy pursuit of his creation, eventually reaching the Arctic. This is where Walton finds him.
They Called Me Mad!: What Victor fears they'll do if he tells people about the monster. They do call him mad eventually, but to their credit, Victor had been delusional with Brain Fever for a time.
Unreliable Narrator: Victor portrays his family as the perfect happy family at first, but if you pay attention he contradicts himself in a few places and the Frankenstein family doesn't look so happy after all.
Adaptational Intelligence: Inverted. While unable to speak upon his birth, the creature soon becomes eloquent and intelligent in the original novel. The various film adaptations often keep him in the brainless stage and never moving on, to the point he's more well-known for being a lumbering brute who barely understands speech.
The Aloner: Because everyone's so damn terrified of him.
Anti-Villain: To the point that many sympathize with him much more than they do with his creator.
Brown Note: When Victor first sees him, the Creature's monstrous appearance makes Victor have Brain Fever.
Byronic Hero: Like Father, Like Son. The Creature is incredibly eloquent, brilliant, and persuasive in his best moments. He is also filled with characteristically Byronic anguish and despair due to being cut off from humanity as a result of his unnatural birth (or creation, depending on how you look at it). Some literary critics have interpreted the Creature as Victor's dark side.
Cry for the Devil: The last section of the book demonstrates that the Creature was formed by his surroundings, rather than born evil.
Cycle of Revenge: The Creature seeks revenge on Victor for abandoning him, causing Victor to hate him in return. Basically, one act of hate leads to the other retaliating in kind until Victor dies a miserable man and the Creature is so horrified by what he had become that he commits suicide.
Evil Vegetarian: Averted. At first he's benevolent while only eating things like roots, berries, and nuts. Though later when he turns evil, he kills a rabbit so Victor can eat it. It's unknown whether the Creature himself eats animals while he's evil, though.
It's also possible that he's a straight-up herbivore and unable to eat meat, although it isn't made clear.
Face–Heel Turn: Initially is born with benevolent intentions towards humans. Turns evil after humans constantly reject and mistreat him.
Foil: To Victor. Unlike Victor, the Creature doesn't have any family or friends who love him, is forced to live in the harshness of the wilderness, has to self-educate himself, and desperately wants to associate himself with the humans who reject him. However, both the Creature and Victor are Byronic Heroes.
Genius Bruiser: The Creature educates himself very quickly by spying on a girl's lessons through a crack in a wall, growing into a remarkably intelligent, eloquent, and philosophical man. He is also an extremely powerful physical specimen, resistant to cold and injury as well as immensely strong, fast, and agile.
"If any being felt emotions of benevolence towards me, I should return them a hundred and a hundredfold; for that one creature's sake I would make peace with the whole kind!"
Perhaps a bit of hypocrisy there, as there was one man who felt benevolent toward him - the blind man. It was the man's family chasing him out that started him on his murderous rampage.
Instant Expert: The creature is a blank slate... essentially a newborn but with motor skills. He learns to speak and read French fluently in less than a year of watching a family teach a foreigner. After just a few months he's already good enough to read Paradise Lost!
Lightning Bruiser: Of the "Fast-moving Big Bruiser" type. He can easily collect a large pile of firewood without a sweat, and he can easily sprint across an icy mountaintop.
Loners Are Freaks: No human wants to interact with him, let alone befriend him, due to his monstrous appearance.
Made of Iron: The Creature can survive much harsher injuries and conditions than a normal human.
Monster In The Cottage Shed: To observe a peasant family, he hides in their cottage shed so as to not notify them of his monstrous presence and cause them to chase him away.
Monster Sob Story: The Creature tells his back story to Victor over several chapters to entreat him into making him a mate.
No Name Given: Mary Shelley did apparently called him "Adam" in letters to friends. Nowadays readers may simply know of him as "The Creature" or "The Daemon."
Obliviously Evil: During the one of earlier moments of his life he breaks into a old man's house and steals his food because it smelt so good. Only later does he realize that taking without asking leads to others' unhappiness.
Only a Flesh Wound: Averted; when the Creature gets shot in the shoulder, he faints, and it took weeks for him to recover. And he's much stronger and tougher than the average human.
Reluctant Monster: He may look monstrous, but all the Creature really wanted was to befriend and live among humans!
Revenge by Proxy: The Creature decides to get revenge on Frankenstein for its own wretched existence by making him suffer, so he kills Frankenstein's youngest brother, followed by his greatest friend, and then on Frankenstein's wedding day, the monster strangles his bride.
Turned Against Their Masters: An example and a subversion. The Creature doesn't turn on its creator until after its creator (and the local populace) turns on it. This makes the moral of Frankenstein less "Don't create life" and more "Don't create life if you don't plan to take care of your creation."
What Measure Is A Nonhuman: Even with his intelligence and (at the beginning) good heart, because of his unnatural birth, his fearsome appearance, and unchecked strength, the Creature is immediately considered evil by not only by his creator Victor, but also by anyone who sees him. Therefore, despite the Creature practically being his child, Victor has absolutely no remorse over his hatred and desire for the Creature to die, simply because the Creature is not really a human (and looks damn scary to boot).
Foil: To Frankenstein. While Victor was determined to discover the mysteries of creation no matter the cost, Walton is determined to reach the Arctic Circle but is unwilling to continue when his crew want to turn back.