In Irish folk history, Goll mac Morna was the great anti-hero of the Fianna Cycle, just as Finn mac Cumhail was its hero. Far from being a villain, Goll was fearsome and fearless, and a model of warrior's honor. He was Finn's primary rival, but while the two often clashed, they also fought side by side in many battles, keeping each other from harm. The nature of their relationship was complex and intricate, and we should explore a little of Goll's early history to understand it better.
The Fianna were a band of Fir Bolg warriors who served the Milesian high king, or Ard Rig. Ireland at this time was peopled by a number of clans, each with its own web of feuds and alliances. Clan Baiscne, the clan into which Finn would ultimately be born, was the dominant clan in the Fianna at the time of Goll's birth. Named Aodh, meaning "fire", when he was born, Goll was a member of Clan Morna, the chief rival of Clan Baiscne.
Clan Morna was rising in power, and Cumhail mac Treanmhor, head of Clan Baiscne and of the Fianna, saw the threat which they posed to him. He gathered the men of his clan, and under one false pretense or another, he went on a campaign to drive Clan Morna from Ireland, and this he did quite successfully. The sons of Morna fled, some to Britain, some to Lochlann (Scandinavia), some to Alba (Scotland), and others to other lands.
In the years that followed, Cumhail became complacent and corrupt in his seat of power at the head of the Fianna. He raided and looted for his own pleasure and enrichment rather than for the high king's cause, abducted women against their will1, and committed other crimes as well. These were overlooked by the king partially because the Fianna were feared by the other chiefs from whom he exacted tribute, and partially because he feared them himself.
The men of Clan Morna were not idle during their time in exile, and were said to have wrought considerable havoc in all the lands where they ranged. Aodh himself killed the king of Lochlann and put a rent, or tribute, on his family. This was essentially "protection money" which kept him from conducting further raids or campaigns against them. This particular tribute was destined to play a pivotal role in the eventual division and fall of the Fianna, but more on that in its own time.
Aodh, who had grown to be the strongest and most powerful of his clan, eventually gathered his scattered fellows and returned to Ireland, where he led them at the battle of Cnucha (now Castleknock, near Dublin) against Clan Baiscne. Cumhail, having grown a little too fattened (figuratively speaking) during the years of his uncontested leadership, was ill-prepared for the fierce onslaught which Clan Morna brought him. The tide of battle quickly turned against him, and to prevent further bloodshed, it was decided that the skirmish should become a battle of champions.
Accounts vary slightly as to what happened here. Cumhail fought as Baiscne's champion, and some say that he fought a series of the sons of Morna, each of whom wounded him easily and then denied to continue the fight because it was too easy. Others say that he only fought one champion, that being Aodh. In either case, it was Aodh who dealt the final killing blow to Cumhail, but with his last bit of strength, Cumhail struck out Aodh's eye with his spear, and there cursed him and gave him the name of Goll, which meant one-eye.
This major shift in power among the Fianna caused shifts in other areas too: a series of challenges to the high king's throne left the power structure of Ireland (which was tentative to begin with) in a shambles until the ascendance of Cormac mac Airt as Ard Rig some years later. Cormac, a skilled diplomat and a just man, stopped the feud between Morna and Baiscne and brought them both back together under the umbrella of the Fianna.
It was not long after this that a fair young lad walked boldly into the king's feasting-hall at Tara and proclaimed himself to be Finn, son of Cumhail, son of Treanmhor. Later at the feast, the king decreed a hero's reward for any man who could defend Tara from an evil spirit that was about to descend upon the city (see The Life of Finn mac Cumhail 2: Finn's Youth for more details on this event). Finn accepted and succeeded, and as a result was given leadership of the Fianna.
This was no minor insult to Goll, having his leadership taken away from him and given to the son of the man who had deposed him and his entire clan from Ireland. However, Goll accepted Finn's ascendance with composure, declaring his loyalty to Finn and swearing off any grudge against him. Finn returned by swearing off vengeance for his father's death, a precedent-setting oath.
The nobility of these two warriors was inspiring to the others, and the forbearance of personal vengeance eventually became one of the oaths all Fianna had to take. As time passed and battle seasoned them, the pair's mutual admiration for each other grew, each having talents and traits that the other lacked.
Finn's charisma and leadership abilities were far beyond those of Goll's, and a story is told of a stranger who once questioned the presence of the older Goll among Finn's young band. Finn responded with a poem of praise in which he described the virtues of Goll, how he was as strong as the crashing waves of the sea, and brave and stalwart in battle, yet open-handed and faithful to his friends and his word.
Both were unstoppable on the field of battle, but Finn's athleticism and finesse were a stark contrast to Goll's brute force. Goll was often described as the trunk of a great oak tree, which many swords had marked but none could cut down.
Goll was also older than Finn, and wiser, both in the ways of the world and of tactics, and while Caoilte mac Ronan was Finn's closest advisor in personal matters, he invariably consulted Goll when it came to battle-planning. One of Goll's treasures that is often referred to in old stories was the Solustairteach, which meant "shining thing". It was a chessboard made of gold and silver, and Goll and Finn played upon it often.
Unfortunately, Finn's charisma waned with age, and was replaced to some degree with bitterness, and he could no longer manage to keep the peace among their two clans. The issue came to a head one night when Finn challenged Goll's right to claim tribute over the men of Lochlann. This caused the issue of Clan Morna's exile by Cumhail to be brought to the surface again, leading eventually to their return and the death of Finn's father Cumhail at the hands of Goll.
These events were of course sore spots for both clans, and tempers flared. The two clans declared war on each other, and the ensuing skirmishes decimated Clan Morna. In the end, Goll was cornered and killed in single combat with Finn (some sources claim Finn's forces instead starved Goll to death). For a more thorough description of these events, see The Life of Finn mac Cumhail 4: Finn's Decline.
Footnote:
1: You may think that abduction of women is by nature against their will, but it was a fairly common custom in Ireland in those days for a man to "abduct" his wife-to-be and take her to his own dwelling some time before the actual wedding. This was mutually consensual and more ceremonial/traditional than anything else.