Dragon (Dark Sun)
The Dragons of Dark Sun are a type of advanced being. An exceptionally powerful human defiler can pass through 10 stages, each of them marked by the casting a spell of epic proportions. Each spell makes the caster more and more draconic, until full dragon form is achieved with the 10th spell.
The only person ever to have become a 10th stage dragon is Borys of Ebe, who became known as the Dragon of Tyr. After his transformation, he spent several years utterly insane, with no more self-awareness than an animal. He razed cities and destroyed entire civilisations before he returned to himself. He was recently killed by Rkard of Tyr