A Witch family of Ravencrest. On the Coven like every other family.
Jack Pratchett is a classmate of Kelly's. Diane---Jack's sister---is dating Jason Dupray, Mary and Kelly's cousin. Jack was killed by Kelly Daniels in self-defence after he stabbed her.
The eldest son in the family is Greg.
The Pratchetts are in charge of safekeeping any dangerous artifacts that the Coven might possess, locking them all in a Vault in their basement. The Orb of Aka Manah is one such artifact.
Ms. Irene Craven---Principal of Ravencrest High---is a Pratchett by marriage, making her the mother of Jack, Diane and Greg.
Matilda Pratchett---Jack and Diane's grandmother---is a Coven member and secretly a member of the Black Horn. In Season of the Witch, its revealed that she has no knowledge of what's been taking place but stops it as soon as she finds out. However she seems to be actively involved with the events of A Tale of Two Sirens. In Ch.25 of Season, its revealed that she and her daughter-in-law have fled for parts unknown.