The protagonist and narrator of the novel, a lonely, sweet rich girl whose father takes in a girl her own age, Carmilla, after she is found in an accident. The two become fast friends after discovering a childhood link between themselves, but as their relationship grows, Laura's dreams start turning to nightmares and her home life becomes strange and dark the longer Carmilla is there.
- Beauty = Goodness: Laura is as good as she is (at least to Carmilla) pretty.
- Broken Bird: Implied to be one at the end of the book after all she's experienced.
- Damsel in Distress: She is slowly being drained to death by Carmilla, and unknowingly risked a Fate Worse than Death.
- Hair of Gold, Heart of Gold: Laura is blonde and the nicest character in the novel.
- The Ingenue: Laura, who is very kind and innocent (to a rather absurd degree at times, with how often she does not think to associate Carmilla for the creepy things happening around them both).
- Lonely Rich Kid: Her whole life, she's been living in a secluded castle in an Austrian forest with her father and a few servants, having no friends of her own.
The female vampire masquerading as a young ill girl, who both loves Laura and preys upon her.
- Aristocrats Are Evil: She cares very little for peasants and wishes a violent punishment on the hunchback salesman who unintentionally insults her teeth.
- Anti-Villain: While it may not have been the author's intention, Carmilla does come off this way. What keeps her from being a total monster like, say, Dracula, who killed without remorse, Carmilla appears to feel guilt occasionally over what she does, and genuinely cares for Laura.
- Brainy Brunette: Carmilla is very intelligent and educated, and tends to favor scientific explanations over superstition. One good example is how she explains to Laura that the anti-vampire charm she purchased has natural properties based on the material it is made of (or covered with) rather than any higher power. It's quite ironic, as she is a bona fide vampire.
- Cute Little Fangs: Subtle enough that the only character who even notices their sharpness has knowledge of dentistry.
- Dances and Balls: Carmilla was murdered by a vampire after one ball. She remembers it vividly.
- Eerie Pale-Skinned Brunette: Carmilla is described as a beautiful brunette, and while she is usually fair skinned, the book actually averts the trope of pale vampires, because Carmilla is often rosy-skinned after having a meal.
- Ill Girl: She pretends to be one to explain symptoms of her vampirism.
- The Lost Lenore: She is this for the Moravian nobleman who was in love with her when she was alive. His fear that she will experience a Fate Worse than Death if she is killed as a vampire leads him to hide her tomb and enables her to murder young women for more than a century and a half.
- Manipulative Bastard: Manipulates her entrance into her hosts' lives, manipulates her victims into befriending her and even tries to lull Laura into a false sense of security by purchasing an anti-vampire charm and gushing over how effective it is.
- Mood-Swinger: She goes from serene to angry for no apparent reason in Laura's perception (in truth, some of it is her guilty feelings of killing girls).
- Mysterious Woman: To the extreme. Carmilla refuses to tell her hosts her family name, her armorial bearings, the name of her estate or even the country she is from. Understandable, as the truth is something she wants to keep a secret, for the sake of her survival.
- Obfuscating Stupidity: Is fond of doing that, especially with Laura's father. It helps her project an image of helplessness and innocence.
- Our Vampires Are Different: Carmilla can walk in sunlight, has a rosy complexion, and can shapeshift into monsters. She also breathes and has a slight pulse, even when asleep in her coffin.
- Politeness Judo: As befitting a noblewoman, she is impeccably polite and it helps to force her unwilling hosts to drop any questions about her background or her date of departure.
- Serial Killer: She claims that she cannot resist her predatory nature, but she chooses to drain her victims to death. It's shown that she can feed once and leave the victim alive, as she did with little Laura.
- Strong Family Resemblance: Laura finds a very old painting of a pretty woman who looks just like Carmilla, who tells Laura she is a direct descendant of the woman. Of course, it's Carmilla itself.
- Sugar-and-Ice Personality: Carmilla is quite polite to most people and very affectionate to Laura. However, she can be cold as well, even sometimes to Laura when she doesn't want to answer her questions about her past, and expresses disdain towards the lower classes.
- The Thing That Would Not Leave: Once Laura's father asks her if she knows when her mother will return, implying that she should be leaving (although mostly for fear of the malady), she quickly applies some reverse psychology and convinces Laura's father to keep her in his schloss longer.
- Woman in White: She leaves the schloss late at night in her white nightgown and heads back to her tomb, moving as if in a trance. Those who have witnessed her mistakenly believed she was sleepwalking.
- Wounded Gazelle Gambit: Her modus operandi. She pretends to be a fragile, helpless and lonely girl in order to ingratiate herself to her intended hosts.
The elderly owner of the Styrian estate where he lives with his daughter. He lives a quiet life on a small income, with only visits from his good friend General Spielsdorf to look forward to.
- Demoted to Extra: He fades into the background as the story evolves, as Laura begins to focus more and more on her charming and beautiful new companion.
- Doting Parent: He loves his daughter very much.
- No Good Deed Goes Unpunished: He gallantly offered to shelter, feed and care for Carmilla for three months, at no expense for her mother. A wonderfully kind gesture which not only nearly cost him Laura's life, but led to the death of several young peasant women.
- No Name Given: Not once does the story ever tell us his name.
- Skeptic No Longer: Once he seems with his own eyes the truth about Carmilla. Before, he had outright laughed at the idea that his young guest was a vampire.
Comprising of an important looking noblewoman masquerading as Carmilla's mother, a frightful looking black woman and several roguish men. They seem to serve as key figures in the elaborate scheme devised by Carmilla to gain access to her victims by becoming the ward of their male guardians.
- Karma Houdini: We never see them getting punished for what amounts to aiding a Serial Killer.
- Large Ham: Carmilla's mother launches into a theatrical, hand-wringing performance once Laura and her father approach the scene of the carriage crash. Laura instinctively finds it unconvincing, but justifies it to herself by saying that some people just are that theatrical.
- The Renfield: We never get any explanation about who (or what) they are, why they are helping Carmilla and what they do when they're not around her. The only thing we know for certain is that they are willing to play the same roles over and over again.
- What Happened to the Mouse?: We never find out what happened to them.
A friend of Laura's father, he lives on his estate located twenty miles from their schloss.
- Best Served Cold: He patiently gathers resources and makes connections, and eventually lucks out when he finds Carmilla by accident while visiting Laura's father. Afterwards he participates in the vampire's transfixation.
- Determinator: Once he realizes that Carmilla is responsible for the death of his niece, hunting her down becomes his sole life goal.