[W, summer white (?)].
Otherworldly rival of King Arawn of Annwfn, whom he was destined to fight each year. Arawn convinced Pwyll to take his own shape one year, advising him to give but one blow to Hafgan as a second would revive him; Pwyll succeeded and returned to the realm of mortals. Hafgan is often thought to have contributed to the conception of the Green Knight who challenges Gawain and to the Arthurian figure Gromer Somer Joure.