Cúchulainn from FFXII
Scion created to rid the world of its impurities by swallowing them within himself, in opposition to Nabriales the Majestic, scion of light. The world, however, was more filled with impurity and corruption than even the gods dared imagine, and having swallowed it all, the once beautiful Cúchulainn was transformed into a hideous thing, a deity of filth, and so did he turn against his creators. Wherever his feet should fall, there all life withers to dust.
Cúchulainn is an easy Esper to use. He has plenty of HP at his disposal and often heals with "Curaja," which enables his summoner to focus more on combat and less on keeping him alive. When paired with a powerful melee character, they can devastate any lesser enemies that crawl around nearly any location.