Hydia

Hydia is the main antagonist of My Little Ponies: The Movie - which was based on the Generation 1 franchise, which was very different from the current version of the show and more akin to what people associate Care Bears and other "kid-friendly" franchises as being.

Despite this Hydia was depicted as a geniunely malicious villain who had a stereotypical "wicked" demeneor and sought to utterly destroy the world around herself as well as abuse everything for no reason other than she could.

Hydia was especially abusive towards her two daughters, to the point of punishing them for calling her "mommy" - a short-tempered crone and all-around nasty woman she lived within a volcano and cast many evil spells in her eternal crusade against all things "nice".

Ultimately Hydia's plans would see her raise the abomination known as the Smooze, a gargantuan slime-monster that was almost unstoppable and very nearly destroyed all of Ponyville - however in the end Hydia was defeated and both she and her daughters were cast back into the volcano where they presumably remain as outcasts.*


 * - (this assumes witches exist in the modern franchise, which does not seem to show humans existing in Ponyville)&nbsp