Dilys Derwent

From Hpwiki

Dilys Derwent once was a celebrated Headmistress of Hogwarts (from 1741 - 1768, after having been a St. Mungo's Healer from 1722 - 1741). In Harry's fifth year, portraits of this witch hang in various places, and because the persons in these pictures can move from one portrait to another, Albus Dumbledore uses Dilys as a messenger.