One common theory is that Danu derives from the Scythian word for “river,” linking the goddess to the Danube River.
Danu’s spouse is never named, and Danu herself seemed sufficient to give ancestry, power, and wisdom to her decendents, the Tuatha Dé Danann.
There is no information on Danu in mythology other than her status as a divine mother, but some neopagan traditions envision her as a triple goddess.
The Irish mother goddess Danu was the ancestor from which all Tuatha Dé Danann claimed descent. Despite her importance to Irish mythology, Danu largely remains a mystery. She was an ancient deity, and made no appearances in the larger Celtic mythos. Though scholars have frequently sought answers regarding this mysterious matriarch, few definitive details have been found.
Many scholars believed Danu to be a representation of the Danube River.
The roots of the name Danu remain a matter of some debate among etymologists. Scholars who have connected her name to the Danube River point to other Indo-European languages where the word danu means “to flow.” Danu may be a loanword from the ancient Scythian language, in which it meant “river.”
It has also been suggested that the name Danu came from the Proto-Celtic duono, or “aristocrat,” itself derived from the Proto-Indo-European dueno, meaning “good.”
Though Danu was the mother goddess and namesake of the Tuatha Dé Danann tribe, much about her remains shrouded in mystery. Danu was the source of the tribe's common heritage, as well as its nobility, unity, and power. As a goddess of sovereignty and power, Danu would grant gifts to rulers and those of noble birth. Though such gifts varied in value and substance, it is nevertheless clear that the kings, chiefs, and Ollam of the Tuatha Dé Danann all drew their power from her. The Tuatha Dé Danann were creative, crafty, and skilled; it has been theorized that Danu was the source of such talents.
As a mother goddess, Danu was believed to have suckled many of the gods and instilled in them a sense of wisdom. Given the migratory nature of the Tuatha Dé Danann, it has been speculated that she was a wind or earth goddess as well. All things in Ireland depended upon her blessings. Her connection to the earth also tied her to the fairies, fairy mounds, and the many standing stones and dolmens of Ireland.
Many scholars have theorized that Danu was a great river goddess. In many parts of the Celtic world, the most powerful mother goddesses had ties to major bodies of water. The River Danube, one of Europe’s longest rivers, may have been one of many rivers named in Danu’s honor. This theory has been challenged as scholars continue to debate the potential migration patterns of Celtic people and their culture; nevertheless, it remains quite popular.
Neopagan tradition has added much to Danu’s mythos that was not present in traditional Irish lore. The neopagan tradition reveres her as a triple goddess, both in association with the Morrígan and independently. There is little consensus among neopagans as to what Danu represents, however, and she is largely a blank slate for practitioners to use as they wish.
Of all of Danu’s features, the most well-established was her family. All members of the divine Tuatha Dé Danann descended from her in one way or another. Kings, warriors, craftsmen, musicians, tricksters, judges, poets, and athletes all hailed from a single source: Danu. While her husband remains unknown, the matter is largely irrelevant. Irish tradition holds that Danu was the tribe's ancestor of note, rather than any husband or father she might have had.
Eriu, though it should reach a road-end,
Banba, Fotla, and Fea,
Neman of ingenious versicles,
Danann, mother of the gods.
-Lebor Gabála Érenn
Danu did not appear in Celtic or Irish myths, and was known only through the name Tuatha Dé Danann, or “Children of the goddess Danu.” She was described as the mother of the gods in the Lebor Gabála Érenn, though this was her sole appearance in medieval Irish literature. Despite the lack of available information, scholars have nevertheless attempted to derive some sense of the goddess' being.
Other than naming her the mother of the Tuatha Dé Danann, medieval Irish lore made no mention of Danu. No description existed as to the type of goddess she was or her place of origin. It is known only that she was an ancestral mother.
Indo-European language and Celtic studies have linked Danu to other goddesses, such as the Hindu goddess of the same name. She has also been connected to popular Celtic concepts such as the importance of waterways.
One of Danu's strongest connections was to the River Danube, a major European river that Celtic tribes would have followed during their migrations. The river’s name was believed to be Celtic or Scythian in origin, lending credence to this theory. Many believe that Danu was both a representation of and callback to this ancient river, which the Celtic tribes may have considered an ancestor.
Danu's lack of a definitive mythos suggests she was an ancient goddess, and some believe that her name—much like that of the Cailleach—was a title that could have belonged to any number of individuals.
Danu has been connected to a number of important Celtic deities both within and outside of Ireland. Similarities between the name Danu and the name Anu (or Annan), have led some to believe that this face of the Morrígan was in fact the mother goddess Danu. She may also have been connected to the Welsh god Dôn, mother goddess of the Mabinogi; Dôn's gender has never been specified, however, and it is possible that Dôn was a male deity entirely unrelated to Danu.
There are many goddesses outside the Celtic world to whom Danu may have been linked. The Celtic Danu may have had a connection the Hindu river goddess of the same name. Many scholars believed that this Indian-Irish connection indicated the existence of a common Proto-Indo-European river goddess. Other goddesses associated with Danu have included the Greco-Roman Gaia and Demeter.
In the modern neopagan tradition, Danu is both mother and triple goddess. In Irish mythology, she was sometimes seen as the most central of the triple goddesses, as the tribe of the gods was named for her. Outside of Annan, Danu has no clear connection to any other goddess (unless Danu is a title). The goddess' power, characteristics, and personality have little consistency within neopagan traditions, and few myths are attested to her.
Danu has appeared in several pieces of popular culture, including:
In the television series Sanctuary, Danu appeared as the most prominent member of the Morrigan. This iteration of Danu was able to learn English by touching the forehead of Will, one of the members of Sanctuary with whom she shared an intense—if brief—connection;
In the 2000 AD comic series Sláine, Danu appeared as the mother goddess worshiped by the Sessair, the tribe of the namesake character. Though she was capricious and fickle, she ultimately battled primeval forces to defend the world of men;
The name of the Irish folk band Danú may be a reference to the goddess and the Tuatha Dé Danann.