Gwyn ap Nudd

In Insular Brythonic mythology, Gwayn ap Nudd was the god of the underworld.

He abducted a maiden known as Creiddylad after she eloped with Gwythr ap Greidawl, Gwyn's long-time rival. Gwynn and Gwythr's fight, which began on May Day, represented the contest between summer and winter.

Alternative: Gwyn