Anathema Device, Practical Occultist and Professional Descendant in Good Omens. Now living at Jasmine Cottage, Tadfield.
Anathema is a self-sufficient young woman with a Ph.D. degree. She is also a descendant of the ancient witch Agnes Nutter, whose prophecies are very important in this novel, and the closest thing to her ancestor genetic drift allows. During the events of the Apocalypse, she deals with it quite sensibly, if only because she knew it would happen.
To draw Discworld parallels, Anathema is self-sufficient like Susan Sto Helit, and good at assembling odd bits of things into magical equipment, like the traditional witch. However, unlike Susan, she has a professed belief in the supernatural from her childhood, and could be said to be her antithesis in many ways.
Anathema: Greek word, from Anathema, "banished, exiled, excommunicated" or "denounced, accursed".
The name Device was inspired by a Lancashire witch called Alizon Device. Also in the Discworld book Lords and Ladies there is reference to a character called Amanita DeVice, who is also a witch (of sorts anyway.)