Helena, the daughter of Hogwarts founder Rowena Ravenclaw, stole her mother’s diadem and ran off to Albania. Her mother became deathly ill soon after and sent Helena’s estranged fiance, a baron, to find her and bring her back (DH31).
Helena Ravenclaw steals the diadem of Ravenclaw
Date 11th Century
Location in Canon DH31: The Battle of Hogwarts
Type of Event Wizarding world