Hênwen, Hên Wen
In Welsh tradition, an enchanted pig whose offspring were going to cause untold trouble for Britain. She was tended by the magician Coll.
The stories and Triads in which Henwen appears are non-Arthurian – with the exception of a single re-written Triad, in which Arthur chases and tries to destroy Henwen because it has been prophesied that her offspring will worsen the state of the world. After giving birth to several piglets, she dove into the ocean from a cliff at Penryn Awstin. This hunt is reminiscent of his pursuit of Twrch Trwyth in Culhwch and Olwen.
It has been suggested that Hên Wen was the mother of Cath Palug, but that particular animal is also said to have been a kitten raised by Cerridwen, the witch who was also known as Hên Wen.
Source
Triads of the Island of Britain (Welsh ”Triads”) | 11th century to 14th century