The Morrígan or Mórrígan, also known as Morrígu, is a figure from Irish mythology. The name is Mór-ríoghan in modern Irish before the spelling reform, and it has been translated as "great queen" or "phantom queen".

Irish mythology is the body of myths indigenous to the island of Ireland. It was originally passed down orally in the prehistoric era. In the early medieval era, some myths were transcribed by Christian monks, who heavily altered and Christianised the myths. Irish mythology is the best-preserved branch of Celtic mythology.