Laura is a nineteen-year-old woman living a lonely existence in a secluded castle in Styria with her aging father. Yearning for companions her own age, she is thrilled when a carriage accident brings a young woman into her home. Laura feels an intense, paradoxical mix of infatuation and fear toward her new guest, experiencing strange dreams and a growing physical illness as their bond deepens.

Carmilla is a beautiful, mysterious young woman left in the care of Laura's family while her mother travels on urgent business. She is prone to bouts of intense languor and refuses to share any details about her past or family. She quickly develops a passionate, almost obsessive attachment to Laura, frequently making intense declarations of affection while displaying an aversion to funeral processions and religious rituals.

An elderly English expatriate who raises his daughter in an isolated Styrian castle. He is an affectionate, kind-hearted parent but tends to dismiss local folklore and warnings of danger as mere peasant superstition. He easily agrees to house an injured stranger, prioritizing gentlemanly hospitality over caution.

A neighboring nobleman and old friend of Laura's family. He cancels his planned visit to their estate following the sudden, tragic death of his young niece. Consumed by grief, he dedicates himself to tracking down the creature he believes is responsible for killing his ward.

A dominant, persuasive woman traveling with a strange retinue of servants. Following a carriage accident, she manipulates Laura's father into taking in her daughter, ensuring the girl is comfortably housed before immediately departing on unspecified, urgent business.

An eccentric expert on regional folklore and vampirism. He holds extensive knowledge about the extinct Karnstein family and arrives to assist General Spielsdorf in understanding the strange illnesses plaguing the young women of the area.

General Spielsdorf's young niece and ward. She was scheduled to visit Laura at the castle to provide much-needed companionship, but she falls victim to a strange, fatal illness after attending a masquerade ball.

A good-natured woman who serves as a governess and surrogate mother figure to Laura. She provides daily structure and comfort in the isolated castle environment.

The more worldly and vivacious of Laura's two governesses. She assists in managing Laura's education and daily life within the Styrian castle.

A local physician summoned by Laura's father when she begins suffering from exhaustion and nightmares. Upon examining her, he discovers a strange blue spot on her chest and urgently advises that she never be left alone.

A learned man known for his medical acumen and interest in mysterious subjects. He collects documentary evidence of strange occurrences, including the manuscript detailing Laura's experiences in Styria.

The individual responsible for publishing Laura's written account. They frame the narrative as a piece of documentary evidence received from a medical expert, establishing a formal tone for the strange events to follow.