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.
Indeed, an alternate name for the novel is the Modern Prometheus. However, the case could be made that Victor is the one who is actually responsible for much of the suffering that occurs due to his mistreatment of the Creature, which could, in a way, be considered his son. Thus, Frankenstein could be either one, and they could both be considered the villain for their actions.
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, and his actual native language is French.
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.
Artificial Zombie: In virtually all adaptations, he was pieced together from dead tissue by some (poorly-defined) means and given life. Questionable in the original novel, as Victor never states what he did with the gruesome research materials he gathered.
Beauty Equals Goodness: Averted with the Creature, who started out a hideous but well-intentioned individual and only became villainous because of constant mistreatment.
Big Bad: Causes most of the damage in the novel in his pursuit of vengeance.
Blank Slate: Is born without properly working senses, let alone the abilities to speak or write or any maliciousness towards humans.
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.
Calling the Old Man Out: The point of the Creature's meeting with Victor is to do this. He also pulls another one after Victor backs out of his promise to make him a companion.
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.
Dark is Not Evil: Essentially a Deconstruction; the creature was not inherently evil, and could had ended up good, but the mistreatment by mankind lead him to become exactly what they thought of him.
Deadpan Snarker: The Creature; upon hearing Victor say "Just go! I cannot bear to look at you any longer!", he covers Victor's eyes with his hand and says "Now you don't have to look at me."
Driven to Suicide: At the very end of the book, he tells Walton he will commit suicide for being an abomination and having caused Victor to die.
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 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.
The Grotesque: An unusual case, as Victor had gone to great lengths to choose only the best parts for each section of the monster's body (best eyes, best hands, etc.) - unfortunately, cobbling together the parts in such a manner meant that once the monster started moving, he fell squarely into the Uncanny Valley.
"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.
Although it can be argued that, had the old man cared to, he could have put in a good word for the creature and set the rest of his family straight. In all likelihood, the old blind man simply allowed his family to convince him that what they saw trumped what he heard.
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 to make him a mate.
My God, What Have I Done?: The creature after causing Victor to die of exhaustion by provoking him to chase him across the world and realizing that he murdered innocent people for nothing.
Nightmare Face: Apparently his face is this to everyone, including himself.
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.
"Have a care; I will work at your destruction, nor finish until I desolate your heart, so that you curse the hour of your birth."
Self-Immolation: How does he plan to commit suicide? By setting himself afire on top of the Arctic Circle.
Then Let Me Be Evil: After deciding he's had enough abuse at the hands of shallow people, he creature takes a flying leap off the morality wagon.
Tortured Monster: He is fully aware of how much of an affront to nature he is. Thanks to Victor's journal that he finds in the garments he took from his apartment, he also knows that even his own creator hates him and wishes he'd never existed. In fact, by the end of the book, it causes him to consider suicide.
Turned Against Their Masters: An example and a subversion. Though the creature does eventually turn on his creator, he only does so after said creator, as well as ever other person he's ever encountered, turns on him. This makes the moral of Frankenstein less "Don't create life" and more "Don't create life you don't plan to take care of."
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.