A hag is a wizened old woman, or a kind of fairy or goddess having the appearance of such a woman; often found in folklore and children's tales such as Hansel and Gretel.
Hags are often seen as malevolent, but may also be one of the chosen forms of shape-shifting deities, such as the Morrígan or Badb, who are seen as neither wholly beneficent nor malevolent.
The term appears in Middle English, and was a shortening of hægtesse, an Old English term for witch, similarly the Dutch heks and German hexe are also shortenings, of the Middle Dutch haghetisse and Old High German hagzusa respectively.
All these words derive from the Proto-Germanic hagatusjon which is of unknown origin, however the first element may be related to the word "hedge".
As a stock character in fairy or folk tale, the hag shares characteristics with the crone, and the two words are sometimes used as if interchangeable