Esmerelda 'Esme' Weatherwax, the most powerful witch on the Disc and one of Pratchett's greatest characters. A formidable, sharp-tongued, iron-willed woman who could have been the most powerful evil the Disc had ever seen, but chose - and continues to choose, every day - to be good instead. She does not suffer fools, is right about almost everything (a fact she finds entirely natural), and considers the most important magic to be knowing when not to use it.