Abhartach

According to Irish folklore, this man was once a villainous dark magic user and a tyrant who subjugated the population of his surrounding area, and was eventually killed by these same subjects. However, he was buried improperly, and promptly rose again as a vampire to drain the blood of those that had killed him. His grave is still visible, and he was eventually defeated by burying his body upside down, due to advice given by a local druid.