While researching these various folktales, I discovered that vampires are related to or even equated with other folkloric creatures that today are usually categorized as separate from vampires. In these ancient folktales, vampires almost seem to be an amalgamation of several creatures.
VAMPIRES AND WITCHES
Brujah, asema, strix; these folkloric witches were often known to draw energy and life force from their victims, and to occasionally drink blood. Their victims usually included children and the elderly. The Romanian strigoi (a possible folkloric inspiration for Bram Stoker’s Dracula) likely originated from the Roman folktale of the strix, a witch believed to take the form of a screech owl and feed on the life force of children. Even today, we have cinematic examples of vampiric witches; Queen Ravenna from Snow White and the Huntsman (2012) extended her life and beauty by stealing the youth (i.e. life force) from young women, and the Sanderson sisters from Hocus Pocus (1993) sucked the life from children, extending their own lives one day per child.
VAMPIRES AND WEREWOLVES
In many ancient cultures, vampires were synonymous with werewolves. Nowadays, we have these franchises that portray vampires and werewolves as archenemies, but legends throughout Eastern Europe told of monsters that, when alive, stalked their victims in the magical guise of wolves and, upon death, came back as undead blood-sucking monsters. Essentially, werewolves were vampires that had not died yet and vampires were undead werewolves; they're just different stages of a single creature's life cycle. Some prime examples of these werewolf/vampire entities were the Romanian strigoi (a life-sucking witch that could take the guise of a wolf, among other animals), the Serbian vukodlak, and even the lobisomem of Portugal and Brazil has been referred to as both a vampire and werewolf. Even Count Dracula displayed lycanthropic abilities in Bram Stoker's novel, escaping a ship called the Demeter in the guise of a wolf (or perhaps a dog).
VAMPIRES AND FAIRIES
What really surprised me in my research was that there were legends of vampiric fairies. There is a story in the Scottish Highlands of a seductive fairy called the baobhan sith, said to resemble a beautiful young woman with hooved feet, almost like a female variant of the satyr. The baobhan sith preys on young travelers, seducing them and then drinking their blood. They were believed to be vulnerable to sunlight and couldn't cross lines or circles marked with iron horseshoes.
VAMPIRES AND GHOSTS
Some legends claim that disembodied spirits can engage in vampiric activity, possessing individuals and slowly draining their life away. The Sumerian edimmu was believed to be the ghost of someone who was improperly buried or died an unexpected or violent death, which would result in their spirit being denied admittance to the Sumerian underworld Irkalla. This spirit would then wander the lands of the living looking for people to torment, often latching onto unfortunate travelers that happened to come across it. The edimmu would then manipulate the person's actions while slowly sucking the life out of them. Similarly, the Hebraic dybbuk was thought to be a corrupted spirit of someone who had died. It would possess a victim and then draw away their energy.
VAMPIRES AND DEMONS
Legend has it that demons will on occasion accost mortals while they sleep. When this occurs, the demons are classified as incubi (male) or succubae (female). An incubus or succubus will bed the sleeping mortal, filling their dreams with nightmares. When the man or woman awakens, they feel exhausted, almost as if the energy or life has been vampirically sucked out of them. In some areas, sleep paralysis has been attributed to the visitation of such demons, referred to in those cases as mara or "nightmares." Witches are also considered suspects, leading to the phrase "old hag syndrome." Some legends say the incubi and succubae will actually drain fluids from their victims. On occasion, it is believed that children might be born from these molestations. One of the most famous half-demons is the wizard Merlin from Arthurian Legend, who is said to be the son of a nun and an incubus.
Creatures from ancient folklore used to have such variety, and you couldn't classify them as just one type of monster. Now you look at the Hollywood lineup of monsters, all so neatly distinguished. The furry guy's a werewolf, the green woman with the pointed hat is a witch, and of course the one with the fangs is our vampire. Yet with so many ancient vampire legends bleeding into other folktales, distinguishing certain creatures as one particular type of monster becomes difficult. Is the baobhan sith a vampire or a fairy? Is the strix a vampire or a witch? Was Dracula just a vampire, or could we argue that he was also a witch, werewolf, or even a demon?