TLDR: Vile = Mr. Sinister.

Vile Extended Audition:

Originally a mild-mannered scientist married to a beautiful witch, Vile became obsessed with evolutionary and cross-species breeding after failing to save his wife from a rare disease not even her magical powers could cure. Giving his daughter's hand to Lord Zedd at his xenith before Zedd's encounter with the Zeo Crystal, Vile gained unlimited resources to further his research while producing battle-capable monstrosities that helped fuel Zedd's empire's reach.

However, when Rita was assumed dead after being charged by Zedd to find Zordon and the location of the last power coins, Vile started quietly planning his revenge for the loss of his only child while turning himself into his own test subject, transforming himself into a powerful being not even Zedd at his mightiest could topple. 

And now, the moment to finally enact his plans has arrived, with Zedd at his weakest, his empire crumbling to the Machines, and the Earth a rich prize of new test subjects to add his collection too...