The King of the Snakes reigns over the snakes of Serenia from the Endless Desert of Serenia, in which he lives. He became trapped under a rock, where the Wanderer discovered him. When the Wanderer freed the King, and the monarch taught the adventurer the magical phrase "Hiss".
The King can be killed by the player, without any consquences. The spell "Hiss" will still work (although technically you never were given the spell). It is unconfirmed but this action is thought to increase the rate that random snakes will appear on screen in the desert.