King Dark Demon (Real name Smiley) is the main antagonist from the game Dynamite Headdy. He's the final boss from the game, with the intent to completely conquer the puppet world.
Dark Demon appears as a towering, ghastly entity, with no visible body aside from his hands, shoulders, head and face. Atop his head is a green, golden-horned helmet, with a turning key resting on top. His robe and the base for the key is a light blue color, the robe itself obscuring a body, if there is one.
Around his neck, if one if present, is a medallion in the shape of a smiley face, said medallion held in place by two pink and gold shoulderplates and a sky blue chain. On his shoulders sit two green statues that seem to move from time to time; The male statue to the left flexes an arm and holds a spear, the female statue to the right plays a pink-colored harp.
His hands, or gloves if this is the case, are a pale green color, pink cuffs near the wrists. He always appears to be holding a curious sphere, from which power seems to be drawn. Last but not least, his ghastly face is a boney white color, made to look quite frightening. The likeness of his face is the emblem of his reign.
The story behind this demonic being is a little shady. King Dark Demon suddenly appears during the game's prologue and takes everybody from the puppet town that Headdy lives in, either turning them into his mindless minions, or incinerates them if he deems them unworthy. His perilous castle lies on a hill top, completely hidden and guarded by the Gatekeeper. During the events of the game, he forever tries to eliminate the puppet hero, sending the Keymasters after him, and even personally fighting him. In the very end, some things aren't what they seem, when it comes to this gargantuan ghoul...
Headdy — For a vast majority of the game, he completely despises and loathes the puppet hero, calling him a "scrap puppet" when they eventually encounter one another. On the other hand, when brought to his senses and the situation explained, the medallion seems to grow quite affectionate towards Headdy, going so far as to cling to his face.
Heather — Not much relation is seen between Dark Demon and Heather, until near the final events of the game. As her indirect actions influenced his motives, she worked to undermine and reverse what was done. Apparently, she was aware of the hypnotizing of the Keymasters, using Headdy to undo their hypnosis. While loathing her whilst mad with power, he views her in a different light when snapped back in his right mind, looking upon her with the same gratefulness as Headdy.
The Keymasters — Dark Demon uses the Keymasters as his pawns in the takeover of the puppet world. This gives the indication he thinks quite lowly of them, at least whilst power-hungry.
Trouble Bruin — As Bruin is his right hand man, so to speak, for a large portion of the game the cat-bear puppet might be viewed by the Dark Demon in a higher light than the Keymasters are.
In the Japanese version of the game, it is explained that Heather told Smiley that he was to be given to the greatest puppet in existence, as a medal. However, Smiley misheard it, and thought that Heather had said he was the greatest puppet, resulting in him taking the guise King Dark Demon and becoming completely mad with power.