King Sombra

King Sombra is described by Princess Celestia as a unicorn whose heart is "black as night". In person, King Sombra is sadistic, fierce, and cruel to the point of addressing the Crystal Ponies as his "crystal slaves" and appearing to delight in their misery. Though untalkative, he is desperate to retake the Crystal Empire and relentless towards that end. He loves King Thorax even if he doesn’t want to admit it.