Who was Rhiannon the witch?

Rhiannon is a prominent figure in Welsh mythology, particularly in the Mabinogi, a collection of medieval tales. She is often depicted as a beautiful and powerful woman associated with horses and the Otherworld. Rhiannon is known for her enchanting qualities, including her ability to speak to and control horses, and her story involves themes of love, loyalty, and transformation. In one of the tales, she endures trials and tribulations, ultimately revealing her strength and resilience as a character.