Cassandra Trelawney was a celebrated seer. She was the great-great-grandmother to Hogwarts School of Witchcraft and Wizardry Divination Professor Sybill Trelawney. It is unknown whether she was part of the Hogwarts staff, for this is not stated.
Etymology
Cassandra was a princess of Troy. Her beauty caused Apollo to grant her the gift of prophecy. However, when she did not return his love, Apollo placed a curse on her so that no one would ever believe her predictions.
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