Rhadamanthys Dantalion is a fallen from Nocte Regem, Avernus. He was the husband of Phoenica, and father of both Renn and Rui. He is quite wealthy, owning a land outside Nocte Regem, along with a mansion. Although he is kind enough to give his land for peasants to work on, he is stingy about his expenses. Rhadamanthys is a gunsmith, learning from the vampires in one of his travel before settling down. He died of sickness and it was so sudden that he forgot to write a will. This left the Dantalion family fight among themselves for a leader.

Rhadamanthys was named after the mythical king of Crete. He is 173 cm tall and weighs 64 kg.