Bul-Kathos

"A barbarian knows that Bul-Kathos's blood runs through his veins. It is what gives him his power and binds him to his people."

Bul-Kathos, the Immortal King, was a great and ancient king who organized the Barbarian tribes.

Origins
Bul-Kathos was born as part of the first generation of nephalem, in later times referred to as the Ancients. These nephalem wandered the world and adopted numerous philosophies as they spread across it. Bul-Kathos observed as due to Inarius's meddling with the Worldstone how subsequent nephalem generations became weaker and weaker, eventually becoming the race of humanity.

The Vigil
Sharing a strong bond with Fiacla-Géar (a brother or close confidant, depending on the source), the pair shared the secrets of the Ancients of the mysteries below the peaks of Mt. Arreat, of the venerated task put to their people to protect those mysteries, and of the prophecies regarding the dark times ahead. They both agreed that, in order to fulfill their sacred trust, their people must devote themselves to nothing save that charge. However, they disagreed on exactly how the people could best do this. Bul-Kathos believed that only by bringing the tribes together and training them in strict martial discipline could the tribes faithfully concentrate on their goal for generations to come. Fiacla-Géar, on the other hand, believed that only through obtaining a spiritual oneness with the land they had sworn to protect could the people truly appreciate the importance of their role. Both agreed the other's philosophy had merit, and so around the time Bul-Kathos united the tribes, Fiacla-Géar gathered together a small group consisting of the tribes' greatest warrior-poets and shamans and mysteriously retreated into the forests surrounding the area known as Scosglen. Bul-Kathos made a sacred vow to protect both Mt. Arreat and the Worldstone.

Bul-Kathos was given reverence by his people. He was given the honour of sitting upon the Immortal Throne, an honor only ever bestowed to one other individual.

At some point, Bul-Kathos did something to himself that allowed him to linger in spirit form.

The Sin War
"No, little Uldyssian ul-Diomed! Ha! Such a...long name for my...dry throat! I am no servant of...the dour one...I was...am...Bul Kathos..."

- Bul-Kathos after being awoken. In the last days of the Sin War, Uldyssian ul-Diomed awoke Bul-Kathos outside Mount Arreat. Bul-Kathos asked Uldyssian whether he knew the names of Fiacla-Géar and Esu. He became slightly more subdued upon witnessing Uldyssian's ignorance, realizing that a thousand years or more had passed since he'd slumbered. He told Uldyssian that Mount Arreat was not his destination, which made the nephalem all the more determined to go there. The two came to blows, though their fight was broken up by Rathma, who informed him that he intended to take Uldyssian into the mountain. Bul-Kathos protested, but Rathma informed him that Lilith had returned to Sanctuary. In an instant, the Barbarian's demeanour changed, and he granted them passage.

Bul-Kathos later took part in the Battle of the Golden Path, fighting alongside other Ancients as they aided the Edyrem in the battle against Heaven and Hell.

The Hydra
Centuries ago, Bul-Kathos defeated the first Hydra. The great serpent was said to spawn two heads for everyone that was severed. In order to defeat it, Bul-Kathos supposedly pitched the beast into a roaring bonfire, wresting the fang lose in the process. The fang was later fashioned into a wand.

Legacy
"The aid of the Immortal King shall come to those who have earned it." Bul-Kathos is treated as a deity by the Barbarians. They believed his spirit resided within Mount Arreat as part of a last line of defence for any of those who would threaten the Worldstone. It is said that Bul-Kathos will aid those who have earned it.

The term "Immortal King" was also given to the Barbarian Worusk, for his unification of the tribes mirrored Bul-Kathos's historical deed.

In-game
Various in-game items are named after Bul-Kathos. These include Bul-Kathos' Wedding Band, and the Bul-Kathos' Children set.

In Diablo III, more items are named after him: Bul-Kathos's Oath set, Bul-Kathos's Wedding Band ring, and Boon of Bul-Kathos passive skill.

Personality and Traits
"I am not the master of the elements that Esu was, young fool, but Bul-Kathos wields much might of his own!" "And speaks about it even more!"

- Bul-Kathos and Uldyssian while in combat

Bul-Kathos valued martial discipline. He demonstrated a dry sense of humor and had a particular dislike for the nephalem Esu and those like her. He was (and is) renowned for his immense strength, size, bravery, and fortitude.

Bul-Kathos was physically imposing, though when Uldyssian observed him his physical appearance and size shifted. One moment his skin was brown like the soil, and his hair the colour of green grass. The next he wore a kilt and sandals with a golden band around his head. In truth, Bul-Kathos's original body had withered away. Only his spirit endured, and dirt and grass had clumped around it, giving him the semblance of a body.

Bul-Kathos despised Lilith, holding her responsible for the slaughter of his parents.