Many cultures around the world have stories about groups of nine women. In Great Britain they occur in a variety of situations. In Scotland there are references to Nine Maidens, purportedly a group of, and there were a number of wells dedicated to them, but like all similar groupings would appear to have had their origin in pre-Christian times. In Arthurian material, the best known of these groups are the Nine sorceresses, Morgan and her sisters who live on the Isle of Avalon and are both seeresses and healers. Another group occur in the Welsh tale of Peredur son of Efrawg, and these are the armed witches of Caer Lyow. Also in Welsh mythology, we have nine maidens who tend the fire below the Cauldron of the "Chief of Annwfn"; this cauldron is the target of Arthur's raid on the Underworld in Taliesin's famous poem Preiddeu Annwfn.
In Norse mythology, the watcher god of Valhalla, Heimdallr is said to be born of nine mothers, and they are also associated with the World-Mill which created the known universe from the bodies of the Ice Giants slain by Odin and his companions.
The Anglo-Saxon Charm Against a Kernel refers to a character called Noðþe with nine sisters.
In Ireland, the attendants at St Brigid's sacred fire at Kildare are sometimes said to be nine, though sometimes nineteen. Brigid also is said to have gone to Scotland with Nine Maidens to found Abernethy, just as Monenna is said to have come from Ireland with nine female companions. St Brigid appears to have been modelled on the earlier goddess figure Brìde, who was also indigenous to Scotland  and may well have been the tutelary goddess of the Brigantes in North West England.
Beyond Britain, the nine occur in the Breton story of the Korrigan, who along with her nine attendants lured unwary men to their deaths and in the tradition of the Gallicenae; the Nine Maidens who lived on the Isle du Sein, latterly known as the Isle of the Druidesses.
In Greek mythology, the Muses were originally thought to have been a whole series of different groups who, like their counterparts in Scotland, are associated with mountains and wells. Robert Graves in The Greek Myths drew attention to a similarity between groups of ecstatic Maenads and the cave painting form El Cogul Roca Dels Moros near Lerida in Catalonia which has nine women dancing round a spectacularly priapic male.
Brìde - goddess in England, Ireland and Scotland who was the origin of the Irish St Brigid
Cailleach - The Winter Hag aspect of the Mother Goddess in Scotland. Similarly known in Ireland
Cerridwen - the Welsh Goddess who had a cauldron of poetry and inspiration
Monenna - an early Scottish saint who supposedly had chapels on Dumbarton, Edinburgh and Stirling Rocks, and Traprain Law - all important Dark Age sites.
Morgan - the leader of the nine sisters of Avalon linked to King Arthur.
Rán - Norse goddess of the sea