Professor Sybill Patricia Trelawney before  was a witch and professor of Divination at Hogwarts School of Witchcraft and Wizardry. 

She is a Seer.

Trivia: It was Trelawney herself who made the prophecy concerning Voldemort and the one with the power to vanquish him during her job interview with Albus Dumbledore. At the end of the 1993–1994 school year, she accurately predicted the escape of Peter Pettigrew and return of Lord Voldemort.