Laura
The protagonist and narrator of the novel, a lonely, sweet upper-class 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.
- Ambiguously Gay: She never seems to shut up about how slender and pretty Carmilla is, she admits to liking the feeling of being embraced by Carmilla, she casually mentions how much she liked playing with Carmilla's hair, and being "kissed" by Carmilla while half-asleep makes her heart race. Of course, she also mentions several times being repulsed by Carmilla's advances, but even that could be seen as a "the lady doth protest too much" sort of situation, especially since in-universe she is speaking to a male doctor. Whether she feels any conscious sexual attraction to Carmilla is left unsaid.
- Beauty Equals 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 risks a Fate Worse than Death.
- Hair of Gold, Heart of Gold: Laura is blonde and the nicest character in the novel.
- The Ingenue: She is very kind and innocent - to a rather absurd degree at times, with how often she does not think to associate Carmilla with the creepy things happening around them both. Possibly explained by her having grown up in seclusion.
- Lonely Rich Kid: Her whole life has been spent in a secluded castle in an Austrian forest with her father and a few servants, and no friends of her own. The "rich" aspect is downplayed, though: although her family belongs to the upper classes, they are not very rich and can only afford to live in a castle because of the low cost of living in Styria.
- Spoiled Sweet: Laura admits that she was, "a rather spoiled girl, whose only parent allowed her pretty nearly her own way in everything." Still, she's a very sweet and kind young lady overall.
Carmilla
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.
- Blood Countess: Carmilla's real name is Countess Mircalla Karstein and it is revealed that she is an actual vampire, and that she has been killing random women for a very long time. Her obsession with Laura only indicates this trope further. Carmilla was most likely another inspiration for the trope, and she's also an Expy in a ton others.
- 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.
- Cats Are Mean: Her default nonhuman form is a creepy-looking cat, and she mostly uses it when she's preying on people.
- 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.
- Daywalking Vampire: While sunlight is unpleasant and physically draining and vampires are much stronger at night, it isn't fatal for Carmilla and she can move around in the day if she wishes.
- 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.
- Ethereal White Dress: 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.
- I Have Many Names: She is Carmilla, but also Mircalla Karnstein.
- Kiss of the Vampire: Her feeding on Laura is described as literally feeling like someone is kissing Laura's throat, and only barely leaves a mark. It takes a very long time for anyone including Laura herself to realise Laura is being fed on at all.
- Lesbian Vampire: Trope Codifier.
- 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 when she could feed once and leave the victim alive.
- Strong Family Resemblance: Laura finds a very old painting of a pretty woman who looks just like Carmilla, and tells Carmilla she is surely a 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.
- Weakened by the Light: A variation as sunlight doesn't kill or even hurt Carmilla but it is physically draining, to the point that even a short walk in the daylight exhausts her, and she is much stronger at night.
- 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.
Laura's Father
The elderly owner of the Styrian estate where he lives with his daughter. He lives a quiet life on a small income, only looking forward to visits from his good friend General Spielsdorf.
- 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 sees with his own eyes the truth about Carmilla. Before, he had outright laughed at the idea that his young guest was a vampire.
Carmilla's entourage
This group consists 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.
- Dark Is Evil: In contrast to Carmilla herself, who is rosy-cheeked and frequently wears white, the entourage are much more darkness-themed. Their seeming leader in particular is known to Laura as "the lady in black velvet", and her more fearsome companion in the coach is described as black-skinned (it's not clear exactly whether that means "black" as in 'of African descent' or something more overtly supernatural)
- 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.
General Spielsdorf
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. Afterward, he participates in the vampire's transfixion.
- Determinator: Once he realizes that Carmilla is responsible for the death of his niece, hunting her down becomes his sole life goal.
- Vampire Hunter: Sort of - really he's only interested in hunting one particular vampire.
