MLP: FIM's Worst Villain Ever (In Terms Of Sheer Evil)

 WARNING: THIS POST CONTAINS SPOILERS!

I've been on another My Little Pony: Friendship Is Magic binge for the past few weeks.  And with Season 5 in full swing, I've decided to talk about one of the villains.  I am not talking about an ordinary jerk like Diamond Tiara or a dangerous monster like the Bugbear.  No, I am talking about a major villain in the show; one who is a very dangerous threat to Equestria and its surrounding area.  

Starlight Glimmer is the ruler of a small remote village where she has convinced other ponies to give up their Cutie Marks, which are kept in a vault in a cave.  She claims that special talents cause pain and disharmony and that equality is the best way to create friendship.  So all the villagers have an Equal Sign Cutie Mark that acts like the brain implants from Kurt Vonnagut's Harrison Bergeron.  And she is by far the most evil villain in the show thus far. 

Until now most of the villains in the show have been either demonic tyrants like Tirek, or mad gods like Nightmare Moon.  These villains have all been simply trying to spread chaos and darkness for various reasons, but they simply loved darkness.  They also had an evil laugh to make them sound more terrifying.  And they all had tremendous powers that rivaled (and even overpowered), Princess Celestia.  
       Starlight Glimmer on other hand--I mean hoof--is a regular ordinary unicorn.  She does not have a hoard of undead-looking shape-shifters under her command, nor does she have the power to turn Ponyville into a chaotic nightmare.  What she has is her own unicorn magic and plenty of resentment.  And she also has a fair amount of charisma, otherwise she wouldn't be able to convince ponies to willingly give up their Cutie Marks.  
        It is implied near the end of Part 2 that she was jealous of other ponies' talents.  She studied magic like Twilight did, except not as good as other unicorns.  In fact, it could be said that she felt so jealous that she figured the only way to be friends was if everyone was mathematically equal.  And the ponies who live in her village came because they were looking for something that they didn't have in their lives.  This made them easy prey for her.  She would convince them that the only way to be friends is to give up their special talent.  After all, if everyone is equal, no one is better than anyone else (of course this leads to lowered quality of absolutely everything).  In their eyes, she was their friend.  They thought she gave them friendship and love when really she was using them for her own gain. 
   
When the Mane Six come to investigate, Starlight takes away their Cutie Marks by force, hoping to use them to further her ambitions.  But when Fluttershy sneaks out during the night, she discovers that Starlight kept her original Cutie Mark.  When this is revealed the next day, it breaks the hearts of the villagers.  They thought she cared about them.  In truth she didn't, she just wanted control over other ponies.  Knowing that the jig is up for her, she tries to escape with the Mane Six's Cutie marks (which she has kept in jars rather than the vault).  The villagers retrieve their Cutie Marks, and four them help the Six regain theirs.  
       
In short because Starlight Glimmer believes that what she is doing is for the greater good, 
she is a far worse villain than all the previous ones combined.  And all she has is ordinary unicorn magic and resentment.