Mean Six

"Once we get the power of the Elements, no creature, not even "her Majesty" can tell us what to do. Just follow my lead. Got it?"

- Evil Twilight Sparkle to the other clones.

The Mean Six are the main antagonists of the MLP: FiM episode of the same name. They are clones of the Mane Six created by Queen Chrysalis before they end up turning against her.

History
Queen Chrysalis created the Mean Six from trees using pictures she took of the Mane 6, hairs from their manes (in Rainbow Dash's case, her tail), and magically carving their cutie marks into the trees. Their purpose was to take the Elements of Harmony and destroy the Mane 6 in front of Starlight Glimmer as revenge for taking away her army and kingdom, and then destroy Starlight as well.

However, because of Chrysalis' evil magic, the clones ended up flawed, acting opposite to the original counterparts. Evil Twilight could tell that Chrysalis couldn't do much without them. Chrysalis sent the Mean Six to search for the Elements of Harmony in the Everfree Forest.

During the search, Evil Fluttershy got distracted picking on a bird, while Evil Rainbow Dash got bored and flew off. Evil Applejack lied to Chrysalis as to where they were, and Chrysalis gave her and the other three permission to split up and search for them.

Evil Twilight took note of the fact that Chrysalis needed them more than they needed her, and planned to lead the other Mean 5 so they could take the Elements for themselves instead of Chrysalis. She ran into the real Pinkie Pie, who inadvertently revealed to her that the Elements were inside the Tree of Harmony, and told her the location of the Tree.

Evil Rainbow Dash ran into Fluttershy, snubbed her, and flew off.

Chrysalis found Evil Pinkie Pie, laying bored on the ground, while Evil Rarity hoarded random objects, and Evil Applejack continued lying. Chrysalis got angry at them and commanded them to find the other three and bring them back.

Evil Fluttershy treated the animals badly, causing them to get angry at the real Fluttershy (during which a bird curses at her).

Evil Rarity mistook the real Rainbow Dash for her clone, and started taking the items that Applejack packed for Starlight.

When Evil Twilight and Pinkie ran into Fluttershy, Evil Twilight was mean to her and left to get the others, causing the real Twilight to think Pinkie upset Fluttershy, and Pinkie accused Twilight of doing so. Twilight was offended that Pinkie seemingly found the trip boring (when really it was Evil Pinkie that made the remarks earlier).

Chrysalis overheard Evil Twilight's plan to betray her and confronted her, saying she should kill them and start over, but Evil Twilight told her she knew where the Elements were.

Evil Rarity tried to run with Starlight's items, but became tangled in vines. Rainbow Dash tried to help her out with a shovel, but Evil Rarity accused her of trying to take it from her. After she got free, she pulled Rainbow Dash to the ground by her tail and ran off.

Evil Applejack ran into Starlight and Rarity, telling more lies and insulting Starlight, hurting her feelings. After Starlight ran off and Rarity ran after her, Chrysalis and the other Mean 5 reunited with Evil Rarity, telling Evil Twilight to lead her to the Tree of Harmony.

As the Mane 6 and Starlight met up, argued, and reconciled, Chrysalis and the Mean 6 reached the campsite where the Mane 6 and Starlight were headed for, and the Mean 6 trashed the tents for fun, with Evil Rarity stealing everything. Evil Twilight told the other five about her plan, and they got to the Tree of Harmony. The other Mean 5 fought amongst themselves, and Evil Twilight said they needed the Elements to take out Chrysalis. Chrysalis heard this and engaged Evil Twilight in a beam struggle while the other five attempted to take the Elements. As Evil Twilight was about to overpower Chrysalis, the Tree sensed the Mean 6's evil and captured them, melting their skin before destroying them in a flash of light, leaving only fragments of the trees used to create them.

Afterwards, Chrysalis remarks how servants can't be depended on, but insures that she will have her revenge on Starlight one day.

Appearance and Personality
As copies of the main characters, their appearance is almost completely identical, except their colors are dimmer and their manes are messier. Their cutie-marks differ as well: Applejack's shows green apples instead of red, Fluttershy's is blue butterflies instead of pink, Rainbow Dash's is upside-down, Twilight's is more erratic, and the ones that show three of something have two at the top and one at the bottom instead of the other way around.

Despite being clones of the Mane Six, their personalities are completely opposite of the originals: Fluttershy is a sadistic bully, Pinkie Pie is a pessimistic grump, Rarity is a greedy thief, Applejack is a compulsive liar, and Rainbow Dash is a faithless slacker. Twilight Sparkle acts as the leader of the Mean Six, but sees the other clones as incompetent minions rather than trusted friends. Also, none of them have any qualms against betraying their creator for their own gain.

Trivia

 * The Mean Six are identical to the Mane Six when they were under Discord's spell.
 * They are the only villains in the series whose existence was never known to the heroes.
 * Ironically, they were beings created from trees, which is the same origin as their creator in the comics (though they are non-canon due to differing depictions of the Dazzlings' banishment).
 * Assuming Midnight Sparkle in Legend of Everfree is nothing more than a figment of Sci-Twi's nightmares, and not counting the Pinkie Pie clones, the Mean Six are collectively the third speaking villains to die onscreen in Friendship is Magic, the first two being King Sombra and the Storm King (although Verko's fate is left ambiguous).
 * Of those, they are the first with the appearance of regular ponies, and also the first who aren't a king.