Professor Galatea Merrythought was a witch and Professor of Defence Against the Dark Arts from around 1895-1945, holding the position for nearly fifty years. She worked alongside Albus Dumbledore and Horace Slughorn, her former students, but eventually retired. Some considerable time after her retirement, Tom Riddle, another one of her pupils, was refused the chance to take her place, and so jinxed the post so no wizard could hold the occupation for longer than a year. Her ultimate fate remains unknown, although, if she is still alive, she would be over 130 years old.