@Pepsi_Al  
The prediction was less depressing that the actual thing.
 
Yeah we got a dark celestia…but it wasnt even actually Celestia or even a real threat at all, it was just Starlight’s imagination of what an evil Celestia would be in a bad dream.
 
Sure they came up with a design, but it was still a super copout.

Black Goku

@Pepsi_Al  

 
That is unfortunate. Ah well, at least we got some sweet celestia episode

@maverick159: I heavily doubt Nightmare Star would be anything other than a canon foreigner with the way this series has been going, though.

Would be cool if Nightmare Star was the villain in the upcoming movie.

@BellyButtonsAreMagic  
agreed
 
 
@Background Pony #2DAB  
Yeah, Nightmare Star MUST be canon (though this name doesn’t sound any original, i preffer Solar Blaze but that’s just me)
 
AND FOR GOD SAKE MAKE SOME CELESTIA EPISODES ALREADY!!!

Celestia does not need to be the ‘untouchable super good character/guardian/parental figure/teacher’ anymore now that Twilight is solidly her own princess, so I agree with OP, I think Corrupted Celestia is a grand idea.
 
A: Celestia needs an episode or two centered around her like the Sahara needs fucking water  
B: Like BBAM said we need more villains, they’re all gone  
C: It would be terrific for Luna and Twilight’s characters as well, to see that even their sister and mentor respectively is not perfect - she too has insecurities that can build up and take over if left unchecked for too long. Luna’s character especially would benefit from this, seeing as the entire reason Nightmare Moon was a thing, was because Celstia and her vibrant sun were all anyone cared about.

Like, please though? Because on top of Celestia’s poor character being so underused since S1 and S2, I’m pretty sure we need more villains anyway next season with Chrysalis being the only major villain who isn’t Super Dead, in Tartarus or a member of Camp Reformation.

Woah, nice pic.
 
Depending on the personality, near incorruptible good(in some respects) turned evil can be a lot more powerful then someone who simply fell into evil naturally. In reference to the scene in DBS, Black Zamasu was never good like our Celestia, but his capacity for power and tenacity was way beyond his normal evil version of himself. Zamasu was a supervillain with a god complex. Black was a supervillain with a god complex who was also a completely relentless psychopath.
 
That being said, if Nightmare Star, Celestia’s nightmared-repressed emotions, ever escaped her own mind and possessed Ra Celestia as a perfect vessel, or simply took over Celestia and fused with Evil Celestia, there would be very little alive in any Equestrian dimension that could stop her.