Xellos

In the novels, the Slayers group generally abhors his presence, while in the anime he is treated as more of a tolerable nuisance. In the anime, Xellos and Lina seem to have a sort of mutual respect for each other. He seems to enjoy the chaos that follows Lina, and follows her for the sake of fun even if he is not ordered to do so. In the novels Xellos seems to be more distant around her, looking somewhat troubled by the fact that Lina, unlike other humans he has dealt with, is able to see the bigger picture of things and is not tricked so easily.

Zelgadis holds a powerful hatred towards the Mazoku because in the 2nd episode of NEXT, he had destroyed a Claire Bible manuscript which, the chimera thought, might have contained the cure to his appearance. This naturally does not bother Xellos one bit, even though he is the only one who does not tease Zelgadis about his appearance. When Amelia makes one of her heroic, "justice filled" speeches Xellos listens with amusement and mild curiosity, although they do tend to disturb him at times. When she makes endless comments about how beautiful and wondrous the world and life are Xellos becomes extremely weakened, and even cringes at her minor comments.

So great is the effect of these speeches on Xellos that, when forced to fight him, the group has even used one of them as a weapon to render Xellos helpless.

Filia is the only being capable of annoying Xellos. Even though he tries to be polite to her, she continues to insult him and call him names like Raw Garbage (namagomi). Xellos likes to tease Filia by the fact that she is part of the dragon race, he makes comments like " Those of the Dragon Race would rather use violence than trying to compromise", or anything along those lines. Xellos seems to have a personal enjoyment of not only making fun of her, but he seems to like tricking her the most. Her hatred towards him comes from the fact that he killed many dragons during the Kõma Wars (War of the Monsters Fall) 1000 years ago.

By the end of the series, they learn to tolerate each other and are capable of having at least one decent conversation.

Xellos is widely considered to be the most powerful Mazoku under the five lords. As such he is nearly immune to all Black Magic, only the spells that call upon Shabranigdo or the Lords can even faze him; however, he is vulnerable to spells that use the power of the Lord of Nightmares, though given his speed it is unlikely that he would allow someone to cast the spell against him.

Immensely powerful, Xellos is capable of annihilating nearly anything using his own power. This is best shown by his destruction of an entire clan of Golden Dragons. However, he tends to underestimate his opponents, leading to himself getting beaten severely by ValGaav. Like all Mazoku, Xellos can teleport anywhere he can imagine by phasing to and from the Astral Side.

"Additional information about myself: There is much more to me than just how you see me in Slayers... of course it is a SECRET!"