Mabon. [W] Son of Modron. A warrior and hunter among Arthur's champions. Culhwch rescued him from captivity at Caer Loyw, used in the tale as a synonym for the Otherworld. In return, Mabon helps Culhwch seek out Olwen and fulfil the tasks required to win her hand in marriage. He hunts the magic boar Twrch Trwyth and takes a razor from between its ears. Mabon obviously equates with the cult of Maponos, "The Divine Youth," which existed among the pre-Christian Celts, a cult found in the north of Britain and in Gaul. The Romans equated him with Apollo, for he was credited with skill in music. In Ireland the obvious parallel is Mac ind 6g, also known as Aonghus. His mother, Madron, is Matrona, "The Divine Mother," eponymous goddess of the Marne in France. The Cymric tradition has him stolen from his mother three days after his birth. He also survives in Continental Arthurian tradition as Mabon, Mabuz, and Mabonagrain.

Mac an Luin. [I] "Son of the Spear," the sword of Fionn Mac Cwnhail.

Mac cecht. [I] A son of Ogma, god of eloquence. He was the husband of Fotla, one of the three goddess, with Banb and Eire, who asked that their name be given to Ireland. He was slain by Eremon, the son of Milesius. The same name also attaches itself to a son of Snade Teched, who was a champion of Conaire Mor, who accompanied the High King to Da Derga's Hostel. He slew the warrior who had killed the High King and then gave the severed head of Conaire a last drink.

Mac Da Tho. [I] A king of Leinster with two possessions coveted by others-a hound and a boar. To prevent an attack on his kingdom he agrees to sell the hound, but both to Connacht and Ulster. Ailill and Medb of Connacht and Conchobhar Mac Ness of Ulster arrive to feast and take possession of the hound. They find Mac Da Tho has slaughtered his boar for the feast. An argument then breaks out as to how the boar should be divided, with the point of contention being the hero's portion. Finally, the Ulstermen and Connachtmen engaged in battle. Mac Da Tholoses his boar and his hound, but he is able to keep his kingdom by setting his enemies against each other.

Mac Greine. [I] A son of Ogma. He was the husband of the goddess Eire, who gave her name to Ireland. He was slain by the Milesian druid Amairgen.

Macha. [I] A triune goddess of war. As the wife of Nemed, she makes her first appearance. Then, as the wife of Nuada, she is killed by Balor of the Evil Eye at the second battle of Magh Tuireadh.  Thirdly, as the wife of Crunniuc Mac Agnomain of Ulster, she utters a curse that the men of Ulster would suffer the pangs of childbirth for five days and four nights in times of Ulster's greatest difficulty. The curse would last for nine times nine generations.  Mac Mong Ruadh, or Macha of the Red Tresses, is not a war goddess, though her traditions seem to have inherited those of the triune goddess. She is listed as the seventy-sixth monarch of Ireland, reigning in 377 B.C. She built Ard Macha (Macha's Height = Armagh), established Emain Macha (Navan) as the capital of Ulster, and is credited with building the first hospital in Ireland, called Bron-Bherg (House of Sorrow), which was in use until its destruction by fire in A.D. 22.

Mac Moincanta. [I] He succeeded the Dagda as father of the gods. In folklore, however, he became a short-lived "king of the fairies," succeeded by Fionnbharr.

MacPherson's Ossian. James MacPherson of Kingussie, Scotland (1736-1796), published Fragments of Ancient Poetry Collected in the Highlands (1760), which he maintained was a translation of authentic Scottish Gaelic poetry, written by Ossian (Oisin), constituting the Fenian sagas. MacPherson extended this with Fingal(1762) and Temora (1763), the three volumes constituting Ossian. It made a tremendous impact in European literature and reawoke an interest in Celtic mythology. Dr. Samuel Johnson denounced the work as a forgery in 1770. Goethe praised it and it also left a deep impression on Blake, Byron, and Tennyson. Napoleon Bonaparte is known to have carried a copy with him on his campaigns, and he took it with him into his exile on St. Helena.

Mac Roth. [I] Medb's steward, not to be confused with the champion Fergus Mac Roth, who was asked to get Medb details about the fabulous Brown Bull of Cuailgne.

Macsen Wledig. [W] Magnus Maximus, a Roman from Spain who arrived in Britain about A.D. 368. He married a Celt name4 Elen Lwddog, sometimes referred to as Helen, and was declared emperor of Rome by the Legions stationed in Britain. He crossed to Gaul and made himself "western emperor" in A.D. 383. He marched on , Rome, and ValentiniaQ II fled from the city. However, Theodosius, the eastern emperor, fought against him and defeated him in several battles. He was put to death on July 28, A.D. 388. It is argued that the Welsh red dragon banner had its origin with the standard of Maximus. Ammianus Marcellinus describes how the emperor's imperial standard showed a dragon on a purple background. His widow, Elen, then returned with her children to Britain, settling in the area that was to become Wales, where she devoted herself to Christian works and her children became the ancestors of several royal dynasties. Her daughter, Severa, is supposed to have married Vortigern. Macsen Wledig (gwledig means ruler) is the subject of several stories in Welsh myth. In one, "The Dream of Macsen Wledig," he is accompanied in a hunt by 32 crowned kings and has a vision. This is similar to the story of the Irish "Bricriu's Feast," in which 32 heroes accompany Conchobar Mac Nessa to Bricriu's Hall.