Xellos is a high level Mazoku (see Universe section below), who is more than a thousand years old. Xellos was, according to Gaav, created by Shabranigdo and given incredible powers. He seems to serve as a priest/general for various monster lords The remaining three of the five demon lords each have priests and generals that serve them, each created by their respective masters. While most of the demon lords have at least one Priest and one General, in Xellos' case, he alone serves Zelas, making him the most powerful being in the world outside of the 5 higher Mazoku Lords and Dragon gods. Xellos served Hellmaster Phibrizzo (another of the five demons) by request of Zelas in his attempt to destroy Gaav the Demon Dragon King. Gaav stated that Xellos was given power beyond any Mazoku created by Shabranigdo, outside the five demon lords. Dragons fear Xellos and see him as their mortal enemy after he killed half the population during The War of Monster Fall. In the 6th Slayers novel (Vezendi's Shadow), Xellos says his real name is simply Xellos the mysterious Priest. He is also known as Beastmaster Xellos (dub only), "trickster priest" (by many, including himself) and "namagomi" ("raw garbage" by Filia) or simply Xellos. Xellos is sometimes a hindrance, sometimes helpful to Lina and her friends. He claims to serve to goals of Phibrizzo, and in season three that of the Monster race, but his actions do not always appear consistent. His trademark response to any important question is, "Sore wa himitsu desu!" (Literally: "That is a secret!"). Xellos and Lina have a mutual respect for one another, though they are far from friends. The two generally refrain from attacking one another as they are both aware that each one is perfectly capable of destroying the other. A constant duel goes on between fans whether there is a love or hate, or even a love-hate relationship between Xellos and Filia. While he usually maintains his human form during the series, his true form is that of a spinning, pitch black cone that is capable of drilling through and tearing apart enemies and can separate into multiple cones. He first appears in the second episode of Slayers NEXT.