Homicidal, probably insane wizard who built a dark fortress for himself on a remote North Sea island. He hid the island away from both the Wizarding and Muggle worlds with Concealment charms. Ekrizdis was reputed to lure and capture Muggle sailors to his island lair where he tortured and killed them. When he died, the Concealment charms faded and the Ministry of Magic became aware of his atrocities. His fortress, called Azkaban, was infested with Dementors and the very walls were imbued with the evil of the fortress’s erstwhile master. The Ministry was unsure how to cleanse or destroy the dreadful place for fear of releasing the Dementors on the mainland (Pm).
No one knows the origin or nationality of Ekrizdis, and it is doubtful any civilized society would want to claim him.
Torture and pain.