The wizard prison in J.K. Rowling’s Harry Potter series is Azkaban.
Azkaban is a fortress prison located on an island in the North Sea. It is controlled by the British Ministry of Magic and is used to imprison witches and wizards who commit serious crimes. The prison is guarded by Dementors, beings whose presence causes despair and drains hope.
The character most strongly associated with Azkaban is Sirius Black. He is imprisoned there for years before escaping in Harry Potter and the Prisoner of Azkaban. His escape is considered extraordinary because Azkaban is designed to be nearly impossible to leave.
Azkaban is distinct from Nurmengard, another prison connected to the dark wizard Gellert Grindelwald. Durmstrang and Beauxbatons are schools of magic, not prisons. These names are often mixed up because all belong to the same fictional magical world.