The wizarding prison created by J.K. Rowling is Azkaban.
Azkaban is a prison for witches and wizards who commit serious crimes. It is located on an island in the North Sea and is guarded for much of the series by Dementors, creatures that drain hope and happiness from nearby people.
The prison is first mentioned in Harry Potter and the Philosopher’s Stone and becomes especially important in Harry Potter and the Prisoner of Azkaban. Sirius Black’s escape is presented as an extraordinary event because Azkaban is considered nearly impossible to escape from.
Azkaban is often confused with Nurmengard, another prison associated with the dark wizard Gellert Grindelwald. Gringotts, by contrast, is the wizarding bank in Diagon Alley and is not a prison.