They have the ability to become invisible, pass through solid matter, and possess a person or object.
Kapau and Chope pretend to be ghosts to fool Noble. They taunt him for believing in ghosts, which they (incorrectly) believe don't exist.
Pythor implores Garmadon to use a spell that would release the spirits of the Anacondrai Generals, while banishing himself. Lloyd perform the spell and the spirits emerged from the realm, shocking everyone with the sight of actual ghosts. The Anacondrai Generals banish Chen and his followers to the Cursed Realm, ending the war. With their task completed, the spirits returned Pythor to normal size and thanked the ninja for freeing them and moved on to the Departed Realm.
At the end, an unnamed ghost escaped the Cursed Realm.
When the true Green Ninja, his old Master's nephew, arrived at the museum, Morro—still in the body of the Watchman—led him to a backroom where he attempted to attack him with a sledgehammer. The watchman was soon buried under several boxes and Morro left his body to possess several other things in the room, such as a portrait of Chen, a Serpentine statue and a pile of sand. After weakening the Green Ninja, he took possession of Lloyd himself.
With the Allied Armor and the control of the Green Ninja's body, the ninja lost their powers, and Morro journeyed to Steep Wisdom to seek the Staff of the First Spinjitzu Master, now carried by his former Master. He faced the Ninja for the first time, using his power of Wind to easily defeat them. Yet, before he was able to obtain the staff, Wu and the Ninja escaped in the Destiny's Bounty. Undeterred, Morro summoned his Elemental Dragon to chase after them.
Morro quickly caught up to the flying vessel and boarded it, defeating Cole and Jay with ease. He used Lightning to cripple the ship's autopilot and descended into its lower level where he defeated Zane. Morro almost succeeded in throwing Kai out of the vessel, though was distracted when Wu threw his staff out the window. As it was Morro's true objective, he summoned his Elemental Dragon once again and used it to retrieve the staff.
Morro flew to a nearby tavern where he satisfied himself with a drink before interrupting a biker's pool game to decipher the message on the staff. Angered at Morro's action, the biker and his friends surrounded Morro, though the ghost used the Allied Armor to summon Wrayth, and the two defeated the bikers with ease. He then instructed the Chain Master to deal with the Ninja while he located Master Yang's Airjitzu scrolls.
Upon arriving at the Ancient Library of Domu where the Airjitzu scrolls were kept, Morro was enraged to find that the thief, Ronin, had already stolen them and fled to Stiix. He stormed out of the building, but not before he gave one of the guards his autograph and took a selfie with them.
Morro soon arrived at a hill overlooking Stiix and summoned Soul Archer to aid him in his quest, as Lloyd was beginning to fight his possession. The two descended into the city and confronted Ronin at his shop. Unfortunately for Morro, the Ninja arrived and Morro ordered Soul Archer to hide so they could locate the scroll. Once the Ninja succeeded, Morro summoned several more ghosts and chased after Ronin, eventually claiming the Airjitzu scroll. He in turn was pursued by Kai though used the martial art to ascend into the air where he summoned his Elemental Dragon and escaped.
Morro used the Armor to release Bansha and Ghoultar from the Cursed Realm, hoping that they would be able to decipher the next symbol on the staff. Bansha revealed that it was the Sword of Sanctuary, kept hidden in the Cloud Kingdom, which was only accessible from the Blind Man's Eye. As the only way to reach the phenomenon was to ascend the Wailing Alps, Morro ordered his forces to the Samurai X Cave, intending to possess one of the Ninjas' mechs.
At Yang's temple, the ninja were in search of the Scroll of Airjitzu and were warned of the curse of becoming a ghost. After finding the Scroll, Yang greeted them and told them of the danger of staying before sunrise. The ninja then race out, though Cole has to retrieve the scroll and becomes ghost, due to the curse. However, since he was not trapped in the temple, he retains his free will.
Yet, before they could take one of the mechs, the ghosts were ambushed by Nya in her Samurai Mech. While she was unable to damage the ghosts, the samurai succeeded in destroying the Allied Armor, thus destroying the way for Morro to summon reinforcements. Ghoultar quickly possessed the mech however, turning it into Mech-enstein, and the ghosts chased Nya and Ronin from the cave. Unfortunately, it soon began to rain and the Master of Wind summoned his Elemental Dragon to head to the Wailing Alps.
Morro used the Mech-enstien to ascend the Wailing Alps, though at the same time Lloyd was growing stronger and fighting his possession. Upon realizing they were being followed by the Ninja, Morro was encouraged to abandon Lloyd's body by his companions, though the Master of Wind reminded them that only a Spinjitzu Master could find the tomb. He did, however, allow Bansha to create an avalanche, and the ghosts continued their ascent.
As they neared the Hanging Temple, the ghosts discovered that the Ninja had survived the avalanche and were climbing even faster. Morro abandoned the mech and ordered his allies to stop them while he continued climbing. Yet, even after calming the winds that plagued the mountain, Morro failed in reaching the Blind Man's Eye.
With his failure and Lloyd's continued resistance, Morro became increasingly agitated. However, Bansha quickly made contact with Fenwick, the head writer in Cloud Kingdom, and made a deal with him to let them in the back way. Morro was shown to where the Sword of Sanctuary was kept and upon retrieving it, encountered the Ninja. Due to being able to see their next move within the blade's reflection however, Morro was able to dodge their attacks and escape back to Ninjago. Yet the Ninja followed, quickly catching up to them, and with Lloyd gaining control of his body momentarily, lost the sword to Kai.
Morro and his ghost companions moved to Stiix were they took up residence in the remains of Ronin's pawn shop. Bansha then contacted the mercenary, ordering him to bring them the Sword of Sanctuary in exchange for his curse being removed.
Ronin soon arrived with the sword in hand and, after Ghoultar inspected it to make sure it wasn't fake, presented it to Morro. The Master of Wind used it to determine the location of the tomb, though he went behind Ronin's back and possessed him. With Ronin's body, he contacted the Ninja and lead them on a false trail to the Caves of Despair. After the message was sent, he left Ronin and taunted Lloyd by telling him to regain strength, as they will be leaving for the real location of the tomb.
Taking possession of Lloyd once more, Morro journeyed to the tomb with the Sword of Sanctuary and passed the first two traps with ease. On the third trap, he eventually met up with the Ninja and dueled with them. Soon, he was fooled by Kai and was trapped, but escaped his enemies.
However, he caught up to the Ninja at the First Spinjitzu Master's resting spot, holding an extremely weakened Lloyd in one arm and threatening to hurt him with his sword if they didn't give up the Realm Crystal. After a while of stalling, Kai intended to fool the ghost again, coming out as a success because of the ninja regaining their power and the plan only backfiring when Lloyd was sent plummeting into a river, drifting away and leaving the Fire Ninja and Cole to save him while Zane and Jay took care of Morro. The Master of Wind was too clever for them, however, and escaped with both the crystal and the sword in his hands.
The ghosts regroup with Morro who appeared with realm crystal and the trio escape through a portal made by the Realm Crystal.
Morro's army of ghosts overtook Stixx, which left the citizens either imprisoned or in hiding. Various trucks from Chen's Noodle industry arrive at the docks, with one truck driven by Master and Misako being halted by Morro. The ghosts look in the back of the truck, only to find that it's suspiciously empty. Master tells Morro that the Ninja will defeat his army of ghosts, but they can still end the occupation without a further conflict. Morro disagrees with Master, and has him and Misako imprisoned with the other civilians.
On New Year's day, Morro used the Realm Crystal to return to the city of Stiix, where he opened a portal to the Cursed Realm. After briefly conferring with the weapon masters about the Preeminent's status, he expanded the portal and ordered the Ghost Warriors to prepare the city for their master's arrival.
The Ninja shortly arrived to the city of Stiix with Lloyd by their side to stop the Preeminent from crossing over to Ninjago.
The ghosts and Morro were alerted to the presence of the supposed Green Ninja, whom they caught with ease. The ghosts brought the Green Ninja to the center of town where Morro mocked it and pulled off the hood, only to discovered that Nya—the Water Ninja—was underneath. Using his power of wind, Morro was able to repel her water attacks until he noticed Lloyd trying to sneak by. He confronted the real Green Ninja and—using the Sword of Sanctuary—was able to prevent him from reaching the Realm Crystal. However, Ronin arrived and distracted Morro by raining down his wealth, which allowed Lloyd to get inside the building and reach the Realm Crystal. Yet Morro managed to get inside before Lloyd destroyed it and delayed him by reminding him that destroying the crystal would ruin any chances of saving Garmadon. His delay worked as the Preeminent arrived and dragged Lloyd into the Cursed Realm.
As The Preeminent emerged into Stiix, Morro confronted his old master and captured Misako. Then he fought Ronin to get the Sword of Sanctuary back, but Lloyd showed up to get the Sword, and battled Morro in other realms. Morro returned to Ninjago and trapped Lloyd in another realm.
Unfortunately for the Master of Wind, Nya unlocked her True Potential and sank The Preeminent. As the creature fell into the water, Morro used his wind to keep himself above the ocean, Wu arriving on his Elemental Dragon to help him. As he struggled to stay away from the water, he was soon grabbed by his master. Morro soon realized that his fate had been sealed, and handed his old master the Realm Crystal before sinking into the ocean and dissolving.
With the Cursed Realm destroyed, most of the ghosts (except for Clouse who escaped) were all sent to the Departed Realm.
He dug up the teapot from a pile of junk in the harbor of Stiix and entered an unknown location, where he used the teapot to summon Nadakhan, which freed him and was granted three wishes. He wished for his book of spells, but it backfired when he picked up the book, as it turned into ash due to being burned by the Ninja. He then wished for him to become human again, but suffered intense pain, as Nadakhan described the transformation from ghost to physical as a "painful process," leading to Clouse to use his final wish and end up being manipulated by Nadakhan into wishing to be free of all of the pain. Nadakhan then used the broad context of the wish to trick Clouse into being absorbed into the teapot, where he was free of the pain at the expense of being trapped within the teapot.
Due to Jay making his final wish, Clouse was freed from the Djinn Blade and restored back to his ghost form, with no memory of the events of the season. He attempted to salvage the Teapot of Tyrahn, only to be noticed by the people of Stiix who still resented ghosts for the destruction and chased him off, preventing him from freeing Nadakhan and ironically sparing him.
- Cole (formerly)
- Yang's Students (formerly)
- Anacondrai Cultists
- Anacondrai Generals
- Ghost Warriors
- Morro, Master of Wind
- Bow Master Soul Archer
- Blade Master Bansha
- Scythe Master Ghoultar
- Chain Master Wrayth
- Ghost Ninja Attila
- Ghost Ninja Hackler
- Ghost Ninja Ming
- Ghost Ninja Spyder
- Ghost Ninja Howla
- Ghost Ninja Yokai
- Ghost Ninja Woo
- Ghost Warrior Cowler
- Ghost Warrior Cyrus
- Ghost Warrior Ghurka
- Ghost Warrior Pitch
- Ghost Warrior Pyrrhus
- Ghost Warrior Wail
- 44. "The Corridor of Elders"
- 45. "Winds of Change"
- 46. "Ghost Story"
- 47. "Stiix and Stones"
- 48. "The Temple on Haunted Hill"
- 49. "Peak-a-Boo"
- 50. "Kingdom Come"
- 51. "The Crooked Path"
- 52. "Grave Danger"
- 53. "Curseworld, Part I"
- 54. "Curseworld, Part II"
- 55. "Infamous"
- 56. "Public Enemy Number One"
- 57. "Enkrypted"
- 58. "On a Wish and a Prayer"
- 59. "Misfortune Rising"
- 60. "My Dinner With Nadakhan"
- 61. "Wishmasters"
- 63. "Operation Land Ho!"
- 64. "The Way Back"
- If a ghost remains outside of Yang's temple or the Cursed realm by the Day of the Departed they will pass over to the Departed Realm.
- Many people initially didn't believe in ghosts, thinking they don't exist. However, due to the Second Serpentine War and Battle of Stiix, they now believe in them.
- As seen in "Enkrypted," if a ghost is responsible for a crime they will be put in special cuffs that block out their powers.
- The only known way for a ghost to return to mortal form is the Rift of Return.