Probably derived from the old Celtic name Rigantona
meaning "great queen". It is speculated that this was the name of an otherwise unattested Celtic goddess of fertility and the moon. The name Rhiannon
appears later in Welsh legend in the Mabinogion, borne by the wife of Pwyll
and the mother of Pryderi
As an English name, it became popular due to the Fleetwood Mac song 'Rhiannon' (1976).