Zlo

Zlo is a powerful demon lord who commanded a vast portion of Hell. His power actually has the disadvantage of ageing his physical form and so has managed to gain the ability to use the forms of his demon servants upon disintegration and the willing slaves allow themselves to be consumed by him, and the cycle continues. Bored of his existence as being in need of others and maybe being seen as not strong enough to be independent escaped through a Hellmouth in an unknown point in time and the ordeal kills him. However, he takes the form of a human and remains immortal from then on, establishing a cult that follows his will that manages to stretch out all over the world.

He eventually finds his way to Sunnydale in the present day, seeing the potential of power in Sunnydale because of the Hellmouth beneath it. Zlo then faced with Buffy and her friends numerous times, becoming obsessed with her destruction and attaining power. She has even managed to kill him twice. However, due to his ability to possess others, he has managed to regain his demon form on Earth, which actually does not rapidly age. He ultimately loses his new powers and has to settle with that of a vampire body, something which he finds totally humiliating.

Personality
Zlo is known to be bitingly dry and sardonic with his dialogue, mocking his minions with such a wide vocabulary that it practically confuses them. He also has a ferocious temper, which can be set off very easily, especially when his power comes into question. This is shown when he kills one of his own sired vampire slaves after he made a comment that if Zlo was as powerful as he says he is - why is Buffy still alive. His rage generates strong grudges, which is why he so desires to kill the members of the Scooby Gang. Despite his intense fury and obsessions, he has this twisted sense of 'nobility', as he has the power to kill Buffy simply by taking over her form when she kills him, but chooses not to as he has this respect for Buffy at being so 'persistent' in stopping him and finds torturing her and her friends until death much more fitting.

Zlo loves violence and discord and his plans are often spontaneous and thought of on the spot, making him unpredictable as he 'makes it up as he goes along'. Zlo is also constantly seen as arrogant and megalomanic, seeing everything as either his subordinate or as a nuisance. Even Buffy, who has defeated him time and again, is nothing but an insect in Zlo's eyes.

Appearance
Zlo has two forms, always two, no matter what form he takes. It all depends whether he is on Earth or somewhere in the Hell dimensions.

Hell form


Zlo's true demonic form is composed mostly of fire and ash. He takes the shape of a giant black wolf with flames brimming from 'wounds' on his scorched and demonic flesh. His body is held together by the influence of his powerful and volatile soul, but the 'pull' of his soul causes it to collapse slowly, needing him to possess another creature.

His soul appears like a small red sliver of mist that can apparently become invisible, allowing the disembodied Zlo to pass to another form undetected.

Earth form
In his Earth form, he is a young man with jet black hair, tall and looks almost anorexic. His gaunt appearance is due to his ignorance of human 'perfection' and due to the ordeal of escaping his Hell dimension weakening him severely.

His appearance only alters slightly with every new creature. His eyes change in each new species and for some reason, as a vampire, Zlo has blonde hair instead of black.

Sometimes, his Earth-bound form will alter when he feels angered or expressing great satisfaction. He would normally show large fangs (in his vampire form, all of Zlo's teeth become jagged) and his eyes glow.

Powers and abilities
Zlo's most notable ability is his power to take over the form of either a living or undead being and recreate the body to become his 'Earth form'. When he takes on a form, he also takes on their weaknesses. If as a vampire, he is harmed by sunlight or silver, but his demon powers allow him to be much stronger and durable than any other vampire. In fact, he will always be much stronger than any other creature who shares the same race as him, becoming more powerful than any Slayer when in a human body. His other abilities are fairly generic for demons, such as superhuman reflexes and strength. He retains these powers with every form. In his current vampire form, his powers are slightly enhanced by consuming blood.

Trivia

 * It is unknown which particular hell dimension Zlo comes from. Zlo never reveals this, only mentioning it as 'up there in the top three worst plains of existence' or 'a place so bleak, so terrible and so full of desolation and woe - it's a wonder anyone stays there'.
 * Zlo is actually a Czech word for 'evil'.
 * Zlo's truly demonic form is never seen, even having a relatively human appearance when he actually attains demon form again.