Meng the Demented

Meng the Demented was an emperor of the mogu empire. According to the Repository in the Mogu'shan Vaults, he was the most foul and maniacal ruler to ever abuse the imperial throne. An obscure passage in an ancient text suggested that when Meng the Demented lost his balance, he lost his mind.

Trivia

 * Meng the Demented is voiced by Marc Graue.

Speculation
While Meng's insanity could simply be natural, it's possible that it was actually Mogu'shan Palace's proximity to the Heart of Y'Shaarj that caused him to lose his mind. This could be further supported by the shadow-based nature of his abilities.