The Black Prince was a member of the Greater Nobility at the zenith of their power and technoloy. He is mentioned twice once in the second last Vampire Hunter D novel and again in the last novel. He is said to have been one of the Three Vampire Kings under the Sacred Ancestor who ruled over the entire Nobility.
It is said by a Vampire Frontier Hunter to D that the Black Prince was one of the oldst, most cunning and most intelligent of all of the Nobility at the time. He controlled a third of the entire frontier and had 250 Greater Nobles and 18,000 lesser Nobles under his Command at the height of his power. It is suspected that he was also commiting brutal experiments on Vampires and Humans when the Nobility began to decline in 4,000 CE at the same time as the Sacred Ancestor but was generally less succesful with his as he did not have the same knowledge and experience as the Sacred Ancestor had in such manners.
He was finally imprisoned for all eternity by his own family and followers due to his brutal experiements and his insatable appetite for women, blood and knowledge on the nobility.