Y Ddraig Goxh (The Red Dragon), Wales Coast Path

The Red Dragon of Wales is first mentioned in the story of Vortigern.  Vortigern wishes to build a castle and in breaking the earth wakes two sleeping dragons, one red and the other white.

This became a common motif in medieval Welsh literature, most famously in the story of Llud in Mabinogi, who must calm the battling dragons as part of his quest, which he achieves by feeding them mead until they fall asleep and are buried in Snowdon, where Vortigern would build his castle.