Cenarius

The romance between Elune, the beautiful humanoid goddess of the elves, and Malorne, the great magnificent stag, birthed a creature like the world had never seen before, Cenarius.

Appearance
Cenarius is a giant creature very much like his father, standing on four legs and frolicking through the woods at great speeds. He, however, is centaur-like in that he possseses an elf like torso.

Background
Elune had birthed Cenarius, but his mortality made him unfit to be raised by a god like her. So he spent his young years with his father, Malorne. His father tasked his other woman, Ysera of the green dragonflight, to mentor her new step-son. Her love for him was unmatched by any.

She taught him how to sleep, and not like that of a normal mans, but instead to access a whole nother world. Here he was powerful and cunning and could do anything his mind saw fit. Large tree sprouted wherever he wanted them.

Though it's unsure exactly who he mated with, his children were much like he in their appearance. Dryads, with their high pitched voices, skipped lovingly through the forest to hug treees. The keepers were more prudish and reclusive, staying in their small, little groves like their father.

His most successful and yet most undeserving children were the bastards known as centaurs. According to the Warcraft 3 manual, Centaur were Cenauriuss' bastard children. These inglorious conquerors created a massive empire that spanned across the length of Kalimdor and committed genocide against the tauren.

War of the Ancients
A long, long time ago the world blew up thanks to the efforts of Azshara, queen of the elves. In the rabble, Cenarius took it upon himself to assert his leadership over the elvess and force them to never again be able to practice arcane or fel magic. He taught them peace. He taught them dignity and not to sellout to demons. Druidism became their chief belief and they built their entire civiliztion around it.

Ten thousand years later the orcs came and killed Cenarius using the same magics he had banished.

Cataclysm
Finally Cenarius came back to life conviently to kill Ragnaros, the Firelord, who had wanted to tear down the world tree since its creation. In this glorious blaze, fire would reign supreme and all would know Ragnaros's might. Cenarius couldn't allow this. He rallied the Cenarius Circle and invaded the Firelands, killing Ragnaros with a bunch of adventurers.

Legion
Cenarius was just minding his business in the Broken Isles, tending to nature, when Xavius interupted. BAM. He infected the demi-god with the infection of the nightmare itself. He now wants to kill ALL the adventurers that'd dare try to stop his new lord and master, Xavius.