Bartholomew

Professor Bartholomew was the Potions Master at Hogwarts School of Witchcraft and Wizardry at some point between the 15th and 19th centuries. He was working at Hogwarts during the same time as Charms professor Fortinbras, and he was the only one she trusted with her search for the Cursed Vaults. Sir Nicholas de Mimsy-Porpington knew him.

He died at some point before 1887 and did not become a ghost.