The Overlord (MLP: MOH)

The Overlord is an evil spirit and the main antagonist of seasons 2, 3, 6, 7, and 8 of My Little Pony: Masters of Harmony. He is also the source of all evil and the embodiment of evil, thus making him the true antagonist of the series and is also one of the main antagonists of the series, along with Pythor and others.