Some names of famous fictional witches are Medea, Baba Yaga, Morgan le Fay and Holda. Isobel Gowdie was a real 17th-century Scotswoman who famously confessed to practicing witchcraft.
Medea is a witch from Greek mythology. She was the daughter of the king of Colchis and the niece of the great witch Circe. Most accounts say she served the witch-goddess Hecate as a priestess. She is famous for the magical aid she gives to Jason on his quest to retrieve the Golden Fleece and her fierce temper.
Baba Yaga is a witch from Russian folklore who lives in a remote hut and is said to be the devil's grandmother. Although she eats human flesh, especially that of children, she is not considered completely evil, and is sometimes asked for aid and advice by heroes. Her aid is difficult to come by, however, as she ages one year every time she is asked a question.
Morgan le Fay is a witch from Arthurian legend. There are two conflicting portrayals of her. In one she is Arthur's adversary, always trying to instigate trouble against Arthur and get him killed. In the other, she is a powerful healer who is associated with the Isle of Avalon and the nine queens of the Isle of Fortune.
Holda is not actually a witch but a Germanic goddess who is the patroness of witches. She is also the goddess of domestic arts and winter, and collects the souls of children who die before they are christened.