Shadowfright

Shadowfright, who is sometimes called Larry by his subjects, is the main antagonist of the second arc (sometimes called the Nightmare Arc) of the My Little Pony: Friendship is Magic comic series.

Shadowfright leads the Nightmare Forces. Their origin is not revealed, but they joined with or possibly even created Nightmare Moon (possibly the outside force who magnified Luna's jealousy and bitterness to transform her, although the TV series may yet reveal a different villain to be this force). They told her what to do to get ponies to fear her, and she promised them a kingdom of their own. When the Mane 6 used the Elements of Harmony to restore Luna and destroy the evil in her, Luna thought the Nightmare Forces would wither and die without her. Instead they went to the moon where they would be granted one more chance through the cycle of the new moon.

In Issue 5, the Nightmare Forces gave the Mane 6 nightmares, and captured Rarity, taking her to the nightmare dreamscape on the moon. In Issue 6, Shadowfright was successful in turning Rarity into their new queen, Nightmare Rarity. He and his minions gave the other ponies nightmares as they traveled to the moon to rescue Rarity, but were pulled out of the nightmares by Spike and Luna. Shadowfright, hinting at a secret Luna kept from everypony, tried to convince her to become Nightmare Moon again. She declined, and Shadowfright revealed Nightmare Rarity.

Shadowfright has the appearance of a dark ghost, but is bigger and darker than his minions. He also gets angry whenever they call him Larry. The first time one of them does this, he grabs him by the throat; the second time, he raises a hammer above his head.

Issue 8's summary mentions that the Nightmare Forces will attack Ponyville, and fight Celestia, possibly overwhelming her.