The Overlord

The Overlord is an evil spirit who serves as the main antagonist of seasons 2 and 3 of LEGO Ninjago: Masters of Spinjitzu and the main antagonist of My Little Pony Transformers Prime: Twilight's Kingdom.

History
When the First Spinjitzu Master created Ninjago, the Overlord was brought to life and battled the First Spinjitzu Master for Ninjago. But before the Overlord could claim Ninjago, the First Spinjitzu Master split Ninjago in half, with the Overlord banished on the dark half.

My Little Pony Transformers Prime: Twilight's Kingdom
The Overlord later returned to Equestria, intent on stealing all Equestrian magic and having it for himself. But Lloyd Garmadon defeated him and the Overlord was sent to Tartarus, but later he escaped and tried to re-take the magic. He started with stealing Uniorn magic and was confronted by Discord and manipulated him to work with him and take his magic back. He then appears at a magic show and steals every Unicorn magic and transforms into his Golden Master form and starts stealing Pegasus and Earth Pony magic before becoming his possessed Garmadon form. He then goes to Canterlot and drains the guards and Shining Armor of their magic before going to the Princesses to drain their Alicorn magic, but once he enters the throne room, he is shocked and infuriated to discover they have no magic for him to absorb. He then imprisons them in cages and goes to absorb the magic out of Twilight's friends. He finds them and absorbs their magic and then transforms into his dragon form and then turns on Discord and drains his magic and leaves to find Twilight. He finds her and tries to drain her magic, but Twilight is so fast that the Overlord realizes that Princess Celestia, Princess Luna, and Princess Cadance transferred their magic to Twilight and they end up in a fight in which they show equally matched strength, speed, and agility. The Overlord then offers Twilight a trade: her friends', Discord's, and the Princesses' release for all the Alicorn magic in Equestria. Twilight's friends, Discord, and the Princesses tried to tell her not to accept but she accepted it anyway. The Overlord releases her friends, Discord, and the Princesses and drains Twilight's magic and became really strong. Discord then says the Overlord tricked him into believing he could offer him something more valuable than friendship and lied to him when he said that his medallion was given as a sign of gratitude and loyalty and gives the medallion to Twilight as a sign of their true friendship and the medallion reflects a rainbow light off and Twilight gets an idea how to open the box. She and her friends head to the Tree of Harmony and use their keys to unlock the box and the box lets out a rainbow light and the Mane 6 gain Rainbow Power and confront the Overlord. The Overlord tries to fight them by blasting them with his, but

My Little Pony Transformers Prime: The Cutie Re-Mark
When Twilight, Optimus, Spike, and Starlight

Appearance in My Little Pony Transformers Prime: Twilight's Kingdom
In his first form, he is shown to be a liquid blue substance with tentacles for legs and red eyes.

In his second form after absorbing enough Unicorn magic, he is in his Golden Master armor and his tentacles are replaced with two black legs.

In his third form after absorbing Pegasus and Earth Pony magic, he is in his possessed Garmadon form.

In his fourth and final form after absorbing Twilight's friends' magic, he is in his dragon form.

Ninjago: Masters of Spinjitzu

 * The Stone Army
 * The Day Ninjago Stood Still
 * The Last Voyage
 * Island of Darkness
 * The Last Hope
 * Return of the Overlord
 * Rise of the Spinjitzu Master
 * The Surge
 * The Art of the Silent Fist
 * Blackout
 * The Curse of the Golden Master
 * Enter the Digiverse
 * Codename: Arcturus
 * The Void
 * The Titanium Ninja
 * The Corridor of Elders (flashback)

Trivia

 * It is unknown if his spirit can be destroyed. As Zane said "Defeated yes, but can he be destroyed?", it might imply that the Overlord's spirit is indestructible.