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 one of the three main antagonists of the series (the other two being Pythor and Clouse). He is the source of evil and is the one who created The Great Devourer.

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.

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.
 * In the Doctor Aaron's Adventures Series, The Overlord becomes the leader of the Dark Dragon Empire after Malefor's defeat.