The Horned King is in great contrast with his predecessors and successors as he exhibits very few of their outwardly arrogant and narcissistic qualities. He is cold and very composed, showing no outward anger until his plan failed and lunges at Taran when he believes it was his doing (on Creeper's suggestion). He has no attachment to his henchmen (who fear him greatly), throwing them away once he has the Cauldron Born and constantly strangles Creeper (the only comedic aspect of his character) with no retorts. He will do anything to achieve his goals, using Eilonwy's bauble and the oracular pig Hen Wen to gain the Black Cauldron to establish his lust for power and an extreme God complex he is disney's most evil villain.
The main villain was supposed to be Arawn, however the animators felt people would like him better since he has horns (notable examples include Maleficent and Chernabog). They combined the elements of the two to create a lich, though the narrator implies the spirit within the Cauldron is Arawn himself.
He desires to find the Black Cauldron and use its power to unleash an army of deathless Cauldron Born to rule the world. He goes to many lengths to find it, kidnapping Eilonwy for her bauble and Hen Wen because he believes they have powers to locate the Black Cauldron. He is first seen talking to his currently non-animated Cauldron Born on his goals. He is seen again when he enters the mess hall of his castle via magical teleport teleportation. When Taran falls into the room, he instructs him to show the location of the Black Cauldron. Taran then splashes water into the King's eyes (which have an agonizing effect on him) to lead Hen Wen into a chase where they manage to keep Hen Wen away and he is thrown into the dungeon. Creeper reports that Taran and his company have escaped and quietly tells him to send the Gwythaints to follow them. The three are ultimately captured along with the newly acquired Black Cauldron which he then summons the Cauldron Born. He sends them to destroy all opposition, however Gurgi flings himself into the Cauldron to negate its necromancy ability. The Horned King returns to the room where the ritual was performed and finds Taran who he believes the Cauldron's failure was his doing. He grabs for Taran, but is pushed into the pull of the Cauldron which rips him to a skeleton and explodes.
Role in the SeriesThe Horned King, despite his destruction, was resurrected by Malefor due to his ultimate dark heart and being an obscure villain in Disney's canon. To this day, the Horned King's designation involves death, the undead, horror, and nightmares, unless one of the other Lords also has the same designations as him. Not only that, but the Horned King is also one of the few Darkspawn Lords who can wield a dark keyblade. This keyblade has the ability to open dark portals and can allow the wielder to open the door to Kingdom Hearts. Sadly, Malefor prefers to not let the Horned King use this keyblade yet until world domination is at hand for the forces of darkness. also, Malefor beleaves the Horned King's darkspawn abilites are enough for him, cause he doesn't want the horned king to get any ideas about taking over the dark spawn brotherhood. However, a major flaw occurs in A Goofy Movie that involves his function, to create nightmares. When Max had his nightmare, it was asssumed that the Horned King would appear to create the nightmare, but then Cobra appears instead. the Horned King is still the one with the nightmare powers, no doubt about that, but Cobra is the only MORTAL villain to be able to enter the dreams of others that are in this series. the banished realms, while they have their powers, the Bounderies around them hinders their powers to prevent from being a problem, even in dreams. (Aside from those that were to outsmart this funtion.)
Eventually, after staying so long in Hell due to his desire to become a Darkspawn Lord backfiring on him, the Horned King began to loathe serving under Malefor and wanted to get out of the Banished Realms to resume his conquest upon the worlds so many years ago. It just so happened that time that Master Xehanort had decided to enact the Great Cycle plot upon the Worlds, and he needed generals to help him sack every world in the Realm of Light to reconstruct the Universe, and he had chosen the Horned King to be his foremost General in the Army of Emotion Parasites. The Horned King, being the power-hungry addict he is, accepts. Because the Horned King had been one of Master Xehanort's oldest friends since his teenage years, he was spared the usual splitting in two to fill out the ranks of the Great Cycle Army. Besides, he's already undead and doesn't have a heart to give up anymore. However, that does not mean he got a little something out of his re-established partnership to Xehanort. In times of battle, Marwoleath could grow into a humonguous giant called "the Horned God", and wield the power of the Enhanced People's Heart Keyblade forged from the hearts of the 7 original Princesses of Heart and those of the 7 rejected Princesses. However, comuppence is a cruel mistress. After the Great Cycle was completed and The Horned King welcome to live in the new-redesigned world that never was, and played adviser. He was encoutered in an abnormally larged starway, where he taunted the gang for their failure to respect their new superiors, espeically his former assisent Creeper, then proceeds to become his horned god form, basicly, a giantic verson of himself. He was finally beaten by Sora and Merlin blasted the Horned King, weakening him enough to lose his great cycle powers, and was sucked back into the banished realms, were angry betrayed darkspawn awaited for him.