The Morrígan ("phantom queen") or Mórrígan ("great queen"), also written as Morrígu or in the plural as Morrígna, and spelt Morríghan or Mór-ríoghain in Modern Irish, is a Goddess from Irish mythology. (Art: 'While Ireland Holds These Graves' by Fionabus on deviantART.)
The triquetra has been found on runestones in Northern Europe and on early Germanic coins. It presumably had pagan religious meaning and it bears a resemblance to the Valknut, a symbol associated with Odin. The triquetra is often found in Insular art, most notably metal work and in illuminated manuscripts like the Book of Kells. It is also found in similar artwork on Celtic crosses and slabs from the early Christian period.
Rhiannon Rhiannon is a Welsh Moon Goddess. Her name means "White Witch or Great Queen." Just like her name she is a very powerful white witch and healer. There are many variations on this Celtic legend. The following is the one that I have learned. Rhiannon was promised to marry an older man that she did not wish to marry. She went against everyone's wishes and married a mortal Prince Pwyll.
The Morrigan is a goddess of battle, strife, and fertility. Her name translates as either "Great Queen" or "Phantom Queen," and both epithets are entirely appropriate for her. The Morrigan appears as both a single goddess and a trio of goddesses. The other deities who form the trio are Badb ("Crow"), and either Macha (also connotes "Crow") or Nemain ("Frenzy"). The Morrigan frequently appears in the ornithological guise of a hooded crow. She is one of the Tuatha Dé Danann