Souls are the fundamental essence of a being, creature or thing, containing their identity and consciousness. Once a souls' physical form is destroyed, the soul in question will either be sent to the Cursed Realm, Underworld or Departed Realm (Once again being destroyed after being cursed or banished to the Underworld or Cursed Realm will result in the being be sent to the Departed Realm).
- The Overlord is the only known soul in Ninjago who was not sent to the Cursed Realm, Underworld or Departed Realm upon his destruction. Instead, he was left in Ninjago, dormant, as he is part of the balance of said realm.
- Originally, when a ghost from the Cursed Realm would be destroyed, they would reform in the Cursed Realm. This is no longer the case, as the Cursed Realm Itself is Destroyed.
- The Sword of Souls was a special blade (Once crafted in the realm of Djinjago), that could absorb a being's soul upon impact.
- Souls who once were held inside a being that wielded a element (or elemental essence), would be colored based upon the element (or elemental essence), they possessed.