Witches in The Elder Scrolls II: Daggerfall, were found near Daedric Shrines and could do "Daedric Summoning" (would summon the Daedra corresponding to the shrine you are near) if you had a high enough reputation with the Witches and for a sum of gold. The NPC would change from a beautiful woman, to an ugly old woman holding a staff. They were members of the Coven on the Bluff.
In The Elder Scrolls V: Skyrim, Witches are humanoid mages who generally will attack on sight. While they more or less dwell near shrines, they can often be seen on the paths connecting the many settlements of Skyrim, often engaged in a skirmish with other characters.