What last name means your a witch?

None. Witchcraft isn't based on your name. Withcraft is a chosen art of practice. But of course there were/are famous Witches, that perhaps you might be related to if you have the last name of Adler, Virtue, Valiente, Gardner, Sanders, Crowther, Crowley, Ferrar, Thomas, Buckland, Leek, (and more...)