Merlin - Famous for his role in the King Arthur Chronicles

Merwyn the Malicious - Credited for the invention of many unpleasant jinxes and hexes.

Mirabella Plunkett - Famously fell in love with a merman in Lock Lomond but her parents forbade her to marry him. Eventually she transformed herself into a haddock and was never seen again.

Miranda Goshawk - Author of The Standard Book of Spells series, which is the set of textbooks used at Hogwarts

Mopsus - A Greek soothsayer who defeated the seer Calchas in a contest of their powers

Morgan le Fay - Morgan le Fay was the child of the Duke of COrnwall and Igraine. She was a dark witch, and very powerful.

Musidora Barkwith - A famous musical composer, whose unfinished work is now banned since it contained an exploding tuba, that blew the roof top off the Town Hall in Alcherley.