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 figure from Irish mythology who appears to have been considered a goddess, although she is not explicitly referred to as such in the texts.
The Morrígan is a goddess of battle, strife, and sovereignty. She sometimes appears in the form of a crow, flying above the warriors, and in the Ulster cycle she also takes the form of an eel, a wolf and a cow. She is generally considered a war deity comparable with the Germanic Valkyries, although her association with a cow may also suggest a role connected with wealth and the land.
She is often depicted as a trio of goddesses, all sisters, although membership of the triad varies; the most common combinations are Badb, Macha and Nemain, or Badb, Macha and Anand; Anand is also given as an alternate name for Morrigu. Other accounts name Fea, and others.
There is some disagreement over the meaning of the Morrígan's name. Mor may derive from an Indo-European root connoting terror or monstrousness, cognate with the Old English maere (which survives in the modern English word "nightmare") and the Scandinavian mara and the Old Russian "mara" ("nightmare"); while rígan translates as 'queen'. This can be reconstructed in Proto-Celtic as *Moro-rīganī-s. Accordingly, Morrígan is often translated as "Phantom Queen". This is the derivation generally favoured in current scholarship.
In the Middle Irish period the name is often spelled Mórrígan with a lengthening diacritic over the 'o', seemingly intended to mean "Great Queen" (Old Irish mór, 'great'; this would derive from a hypothetical Proto-Celtic *Māra Rīganī-s).  Whitley Stokes believed this latter spelling was a due to a false etymology popular at the time. There have also been attempts by modern writers to link the Morrígan with the Welsh literary figure Morgan le Fay from Arthurian romance, in whose name 'mor' may derive from a Welsh word for 'sea', but the names are derived from different cultures and branches of the Celtic linguistic tree.