Vampires

Vampires have evolved or been created through a variety of means over the millennia though the primary way vampirism has spread is through the Pale Rot. Efforts to cure the illness through esoteric or otherwise magical means result in frequent mutation, creating a wide variety of creatures who fit under the umbrella term of the vampire. Entmylogy.
The condition was named after the first true vampire, a dragon by the name of Vyndiramp the Dire. A healer, they had been afflicted with the hallowing while treating a fellow dragon. In their efforts to cure their affliction they consumed vast quantities of blood from healthy indviiduals while continually using healing magic to remove the symptoms and side effects of this treatment. Though initially hailed as a success the pale rot/hallowing soon mutated, turning the dragon's natural greed into an intense, all consuming desire to drain the blood of his kin. In the end they were slain, their body intombed in a hill and marked with a warning upon the tomb's entrance. Eventually elvish treasure hunters would unseel the tomb many centuries later, and through unknown means, contract the contagion which they named after the mistranslated name emblazoned upon the tomb's entrance.