Coll ap Collfrewy
A magician in Welsh mythology. In the Welsh Triads we are told the story of Hen Wen the sow, who is chased across Britain by King Arthur, who has been told that her brood will bring destruction to Britain. Coll, it is implied, saves her from Arthur while on the run througout the island. The sow is pregnant, giving birth to grain, a wolf, an eagle, and Cath Palug, the earliest Alien Big Cat of Britain.
This Coll is, in an earlier triad, said to have been taught one of the three great enchantments of Britain by his uncle Rudlwm the Dwarf. However, in the Hen Wen triad, we are told that he tended the swine of Dallwyr Dallben in Glyn Dallwyr in Cornwall. What must be understood is that the swine is a supernatural animal, having come from Annwn. It is believed that when one is described as a "swineherd" it is implied that they had a connection with the otherworld1, and were often either magicians or the offspring of a god or goddess.
Coll's fame as a magician lived on through the fourteenth century, when Geoffrey Chaucer mentions him in the company of Hermes and Simon Magus:
Ther saugh I, and knew hem by name,
That by such art don men han fame.
Ther saugh I Colle tregetour
Upon a table of sicamour
Pleye an uncouthe thing to telle;
I saugh him carien a wind-melle
Under a walsh-note shale.
from The House of Fame l.1275-1281
A "tregetour" is a conjurer and juggler, a deceiver.
He also became the basis for the character Coll ap Collfrewy in Lloyd Alexander's Prydain Chronicles. He first appeared in The Book of Three (1964) as Taran's father-figure, more involved in the boy's life than Dallben the magician. He is described as a fierce warrior who gave up that life to become a farmer at Caer Dallben, where he worked for the magician, particularly as the "pigkeeper" of Hen Wen. However, any hint of his magicial knowledge is left untouched; instead, although he knows that Hen Wen is a supernatural pig, he doesn't claim to know how to use this knowledge. This book was followed by the picture book Coll and His White Pig, which was based on the triad of Cath Palug, giving a backstory for Hen Wen the Oracular Pig.
He continues through the series as a father to both Taran and Eilonwy; he is killed during the war against Annuvin in The High King, saying he could hear the horn of Gwyn the Hunter--an interesting point, as Alexander effectively ties together Gwyn ap Nudd and Herne the Hunter, both leaders of the Wild Hunt.
The Three Great Enchantments of the Island of Britain
The Three Powerful Swineherds of the Island of Britain
"Branwen uerch Llyr." The Mabinogion. Various translations; available all over the internet and on E2.
Alexander, Lloyd. The Prydain Chronicles series of books.
Bromwich, Rachel. Trioedd Ynys Prydein. Cardiff: University of Wales Press, 1961. (Sadly, this is out of print; UWP promises every year to reprint it, but they have yet to do so.)
Chaucer, Geoffrey. The House of Fame. Available in The Riverside Chaucer or online at The Online Medieval and Classical Library: http://sunsite.berkeley.edu/OMACL/Houseoffame/houseoffame.html
1. Another example is in "Branwen uerch Llyr" when Mathollwch goes to his "swineherds" for advice. It is interesting to note that the term druid never appears in The Mabinogion, but swineherd often does, with the similar position being held as that of the druids in the Irish tales. Either the native word for druid had already been corrupted into dewin "diviner" or the word now was somewhat taboo, and only reserved as the title for Vortigern's advisors (as I believe they are called in either Geoffrey's history or Nennius'). In the end, I don't actually know; why should the Welsh monks be more reluctant to call them druids than the Irish monks?