The Ghost Warriors were a large army of spirits that were once condemned to the Cursed Realm. In the years following the realm's creation, many people were banished to the Cursed Realm, where their bodies decayed while their spirits were imprisoned within for the rest of eternity.

At the end of the Second Serpentine War, one Ghost Warrior, Morro, escaped the Cursed Realm and claimed the Allied Armor of Azure, which he used to free several spirits and bring them into Ninjago. As Morro fought the ninja, he was aided by Soul Archer, Bansha, and Ghoultar in his quest to claim the Realm Crystal and free the physical manifestation of the Cursed Realm, the Preeminent. Morro would eventually obtain the Realm Crystal, releasing an army of Ghost Warriors into Stiix, which led to a great battle in the city. Soon enough, The Preeminent was released into Ninjago, with Ghost Warriors continuously coming out of it.

When the citizens of Stiix boarded the ferry in an attempt to escape, the Ghost Warriors constructed a walking mechanism for The Preeminent, allowing her to walk into the Endless Sea with her legion of spirits nearby. When Nya unlocked her True Potential and drowned The Preeminent, the Cursed Realm was destroyed and all those inside it were killed, including the Ghost Warriors who met their true fates in the Departed Realm.