My favourite folk tale is irish in origin and concerns a hero called Cu Chullain, who, even from early childhood, was destined to be a warrior after he killd the kings hunting hounds with a ball.
I suppose he would have been considered a berzerker character class in a videogame as, in the heat of battle, he went bonkers and killed everything around him.
His most famous tale is based on a a story called The Tain, it is about a king and queen arguing who has the most prized possessions, eventually its decided that the kings treasure is better as he has a famous bull, but this bull had been born into the queens herd, only, he didnt want to be owned by a woman, so he left and went to the kings herd.
To enhance her treasures, she decides to rent a bull from another part of the country, but the people from whom she intended to rent the bull, find out she would have taken it by force, if they declined to rent. The negotiations break down and so the queen raises an army to take the bull.
A witch puts a curse on the queens enemies and they are defeated, except for Cu Chullain, who is off having some nookie with some woman. So, he starts a guerrilla campaign against the queens army, picking them off one by one as they travel back to the queen, eventually holding them to a stand off be demanding they send their greatest warriors one at a time to fight him, man to man. this goes on for month's. He is visited by a witch before one fight, who says she will aid him in combat if he "loves" her, but, he refuses, and therefore she casts a succession of spells hindering him in combat. Eventually the queen gets the bull as Cu Chullain fights and eventually defeats the witch.
Later he finds and old injured woman and he heals her, it turns out to be the witch again, but during this fight he is badly injured. his father comes to his aid and casts a sleeping spell on him while he heals him, meanwhile, some youths from his guild try to come to his aid and are slaughtered by the queens army.
When Cu Chullain wakes up and finds out, he goes into a berzerk rage and kills 6 of the queens soldiers for every one youth that was slaughtered. This produces another stalemate and the single combat sessions resume, but the queen breaks the rules and sends many warriors against him. Eventually she sends his foster father and his best friend (who he kills) against him.
Around this time, the curse on Cu Chullains army wears off and they head off to battle, to rescue him and fight the queen and king. The queen and king are defeated and retreat, but they still have the bull, when they get home, the bull kills their own bull, but becomes mortally wounded himself and also dies.
Later on, Cu Chullain does die in battle, as the battle progresses, he becomes terribly wounded and straps himself to a pillar, so he can die facing his enemies, but his prowess had wrought such fear in his enemies, they were too afraid to approach him, until they saw a raven land on his shoulder and drink his blood.
EDIT : MORE CU Chulainn stories
http://en.wikipedia.org/wiki/C%C3%BA_Chulainn