@Background Pony #0669
Or Nightmare Moon, or Daybreaker, or Midnight Sparkle, or the Windigos, or Rabia and the Umbrums, or Cosmos, or Princess Eris.

@Background Pony #1B8A
Yeah. That is what the Storm King did. Because in the movie, the Storm King have taken over the entire kingdom of Equestria with his army of Storm beasts, his henchman Tempest Shadow and Grubber, and an armada of airships because the Storm King overthrows all four rulers of Equestria, all of the inhabitants have been captured and/or enslaved, and the Storm King has been dominating Equestria to steal the power of the four rulers of Equestria and use it to destroy Equestria and all who lived there including the Mane Six and the first three princesses that were turn into statues.

If the Pony of Shadows is on here, then why isn’t Nightmare Moon?

@Background Pony #C4AB  
The Pony of Shadows is clearly the least evil of them, since he’s more of a tragic character who never wanted to be a villain in the first place, while Grogar is really hard to judge (because of numerous reasons). However, among the rest, well…I would say that they’re all completely irredeemable at this point.
 
King Sombra enslaved an entire empire and instigated a world war just so he could call himself king, and though the comics gave him a somewhat sympathetic backstory…it is debatable whether or not that’s still considered canon.
 
Cozy Glow was about to rid Equestria of all its magic (which would lead to catastrophe) in a delusional plan to become the Empress of Friendship, and since she’s just a child, it is clear that she couldn’t have a tragic backstory and is probably just a power-hungry psychopath.
 
Tirek took the magic of all creatures in Equestria just so he could be more powerful himself, though at the same time it is clear that he once cared about his brother to some extent and felt personally betrayed when he turned against him. So maybe he could get some sympathy points.
 
Queen Chrysalis is a nasty piece of work, seeing ponies as nothing but a source of food, and is willing to lie, cheat, and manipulate any of them to get what she wants. While she was once seen as only wanting to help her people, it is clear though that that was merely a lie, and that she only wants them around so they can serve her and deliberately kept them starving so they would be more useful to her. Even with her empire crumbling around her, she never could accept defeat, and immediately pledged revenge instead.
 
And finally, the Storm King is full on sociopath who’s regularly destroying entire nations and taking all of their riches and magic, leaves them in shambles, moves on to the next one, and does it all with a smile on his face. He does reward his soldiers when they do something good for him, but only to keep them loyal to him, as he doesn’t care about anyone other than himself…which he proves when, after becoming powerful enough that he don’t think he needs them anymore, he turns on his own minions and goes on to destroy Canterlot just to prove he can. He has no sympathetic backstory, yet is responsible for more misery than most of the other villains.
 
So…with that in mind, I would rank them from least evil to most evil as…Tirek, Sombra, Chrysalis, Cozy Glow and Storm King.

So who here is the most evil?

@Background Pony #096E  
I agree. The most successful villain should be the one from the movie.

The most successful villain would be the storm king by far, because he has an army and loyal followers, conquered half the world, defeated all four Alicorns, held equestria conquered for three days, drained all the magic for him self, almost destroyed the mane 6 and their friendship.

I thought the Pony of Shadows was just an alter-ego to the reformed villain Stygian.

I think either one of these might’ve been better pictures for the Storm King.
 

 

And we still don’t any sirens.

Then Grogar revives Sombra (again) and the Storm King. Then all 7 play a game of Magic The Gathering against the Mane 6, all 7 being Archenemy players and the Mane 6 being normal (actually that sounds like an awesome fanfic idea…)