At an unknown point in time, the Underworld came into existence as one of the Sixteen Realms, becoming intertwined with Ninjago, with fallen warriors who were unable to come to terms with their deaths arriving in the Underworld and becoming skeletal beings known as Skulkin. Over time, the Underworld's population grew in size as battles continued to occur and warriors continued to fall, with deceased animals becoming enlarged versions of their remains upon their arrival. At some point, Samukai arrived in the Underworld following his death and became the leader of the Skulkin. Later, Samukai came into conflict with the sons of the First Spinjitzu Master and was defeated.
An Underworldly Takeover (flashback)
Several Skulkin accompanied Samukai as they surrounded a raging Garmadon. From there, they proceeded to watch their master be defeated, and fell under Garmadon's command as a result.
The Last Voyage (flashback)
Samukai, Kruncha, and Nuckal resurrected Dr. Julien and imprisoned him in the Lighthouse Prison, with Samukai forcing him to create vehicles for the Skulkin. Likewise, he would also imprison the Leviathan there to keep Julien from escaping as a result.
Around a decade later, the Skulkin led an attack on Ignacia Village, under the command of Samukai. After engaging Kai in combat and being attacked by Master Wu, they managed to kidnap Nya and retrieve the Map of the Golden Weapons, calling in a retreat.
The Skulkin would go on to mine in the Caves of Despair in search of the Scythe of Quakes, only for Nuckal to disastrously read the map upside down, hindering their search enormously. After being alerted to the presence of the Ninja thanks to Jay, they clashed with the Ninja, only to be overwhelmed when the Ninja discovered how to perform Spinjitzu. They finally retreated, however, upon witnessing the Earth Dragon coming in to confront them. Later on, Garmadon would comfort their leader on their failure by gloating that it was according to plan.
The Skulkin would later go on to try to retrieve the Shurikens of Ice, only for several of their troops to be frozen by the Ice Dragon. A few of them also tried to ambush the Ninja aboard the Skull Truck, but failed and promptly fell into the icy waters of the Glacier Barrens.
Later on, they attempt to climb up the Floating Ruins to retrieve the Nunchucks of Lightning but are beaten there by the Ninja, only for Samukai to secretly chuckle at the fact events that are going according to Garmadon's plan. Later on, while Kai was being led away by a shadow disguised as Nya, the Skulkin attacked the remaining Ninja and tied them up, planning to proceed to the Fire Temple with the rest of the Golden Weapons in tow, only to be informed by Garmadon that the Sword of Fire was now in their home realm. While driving to a portal to the Underworld, the Skulkin were ambushed by Cole, Jay, and Zane, but ultimately succeeded in their mission.
The Skulkin would go on to keep a lookout for the Ninja while Garmadon and Samukai confronted Master Wu. Upon witnessing the Ninja drop in unexpectedly, the Skulkin attempted to defeat the Ninja but were soundly imprisoned thanks to the power of the Tornado of Creation, trapping them in a massive skeletal Ferris wheel. Later, upon Samukai's destruction, Kruncha was crowned the new King of the Underworld.
Traveling back in time to confront Garmadon, the ninja witnessed the Skulkin in the past, committing their acts of villainy as normal, only for their actions to be altered after Garmadon sabotaged their attempts to kidnap Nya, forcing them to escape and averting Kai's destiny to become a ninja. Thankfully, the Ninja restored the timeline somewhat by giving a captured Nya to the skeletons, allowing their actions to continue on as they were supposed to, with a few select members noting strange phenomena that occurred as a result of the time travel, though ultimately making little of it. Later, while ambushing the Ninja at the Forest of Tranquility, they presumably came into conflict with the future Jay over the three Golden Weapons, losing against the experienced Ninja.
As a result of the destruction of the Mega Weapon, the actions of the Skulkin in the alternate timeline were erased, alongside any of their memories of it. Later, as events continued to transpire, the Skulkin largely stayed out of Ninjago's affairs, with only a few select members going out to interact with the living.
Seeking revenge, Wyplash, Krazi, Chopov, and Bonezai attacked Nya at the Four Weapons, only to fail miserably in their attempt.
Looking to reclaim the Golden Weapons, Kruncha and Nuckal would sneak into the Monastery of Spinjitzu, only for the weapons to reject them, forcing the two to leave them behind and head home.
Plotting a second invasion, the Skulkin gathered at the Fire Temple entrance to Ninjago from the Underworld, only for their plans to be disrupted when Flame arrived, sending them fleeing back into the Underworld and destroying the entrance.
Soundly defeated, the Skulkin would largely stay out of the affairs of living as they originally had, with their king Kruncha and his partner Nuckal mostly acting as regular citizens in Ninjago, doing no harm.
While in the Underworld, the Skulkin were confronted by Garmadon, who explained that the Serpentine intended to reawaken the Great Devourer. With a revulsion towards the snakes and their deity, the Skulkin temporarily let go of their grudge and sided with the Dark Lord once more, coming to the rescue of the Ninja at the Serpentine's underground fortress, where they fought off the tribes, allowing the Ninja to escape with the Fangblades in tow.
After Clouse was banished to the Underworld, several Skulkin converged on his position as he lamented his fate, ironically in the exact same location and situation as Garmadon had been in.
Samurai X-Treme (daydream)
Two Skulkin were present in Kryptarium Prison.
Wu and P.I.X.A.L. try to open a portal to the Never-Realm. But the Traveler's Tea wasn't strong enough. At one point, a portal to the Underworld was opened, revealing the Skulkin, their vehicles, and Lord Garmadon's Dark Fortress.
In LEGO Universe (non-canon)
The Skulkin also appear in LEGO Universe, where they attack the Monastery of Spinjitzu and send it into space. The Monastery crashes on Crux Prime, where the Skulkin happen to be mining Maelstrom Ore for unknown purposes. Seeking to investigate the skeletons' activities, Master Wu sends the Imagination Ninja, Neido, to monitor the Skulkin and stop their plans.
The Skeleton Army is made up of skeleton minifigures with torso, leg, head, and arm pieces. They wear belts and armor that is colored red, blue, gray, or white (their elemental colors). Generals have much larger heads than regular Skulkin, with different details on their scalps; Nuckal has a row of spikes, Kruncha has a helmet, and Wyplash has a stud to attach headgear (although the straw hat fits best).
The Skulkin have torsos with bolts printed above the rib cage. These torsos are new pieces with a colored belt depending on the element (even though they aren't Elemental Masters themselves). The Skulkin have two types of arms: regular arms for holding weapons normally, and sideways arms for holding weapons out to the side for Spinner battles. Both types of arms are bent at the elbows. Unlike previous skeleton figures, Skulkin warriors have black shoes, mainly so they can stand on spinners. The Skulkin wear different types of armor depending on their rank.
The trooper armor has bolts on the top and has metal across the chest with a Skulkin symbol. The sides have spikes over the shoulders that are colored differently depending on the element. The Generals have armor that features the Skulkin symbol and bones connected by straps to the shoulder guards. The shoulder guards have colored spikes to represent elements (the only colors shown are gray and white because only Kruncha and Wyplash have them).
Due to Samukai's unique design and high rank among the Skulkin, he has special armor. In the pilot episodes, it is brown, but in "Wrong Place, Wrong Time" and in "An Underworldly Takeover" it is white.
Culture and traits
Generally dimwitted beings, the Skulkin highlighted obedience, anger, ruthlessness, and, bizarrely, stupidity as their main virtues. Described as mostly being made up of those who longed to conquer Ninjago and warriors unable to come to terms with their death, the Skulkin were rather chaotic, though not without some morals, as they opposed the mass destruction that would be caused by the Great Devourer. The Skulkin seemed to also take a great amount of interest in engineering, having created several vehicles and employing the positions of a Chief Mechanic and inventor.
As a result of their inability to come to terms with their own demise and likewise being barred from the Departed Realm, most Skulkin became highly resentful and jealous of the living, longing for their old lives, and likewise became incredibly wild and uncontrollable in their excitement upon returning to Ninjago for the first time in countless years, with their more serious commanders having to reel them in to keep them on track. Additionally, as a result of their undead status granting them a type of longevity, they had a strange perception of time, conceiving five thousand years to be a little experience.
Despite their grudge against Lord Garmadon, the Skulkin still had some honor, as they willingly swallowed their pride and anger over his betrayal in order to save countless lives by preventing the awakening of the Great Devourer. Likewise, following their alliance with the Ninja, their members became notably laxer and more mischievous instead of outright villainous, with most of their crimes stemming from petty mistakes rather than cruel intent.
Powers and abilities
Due to their undead status, Skulkin gained a great amount of longevity and a form of indestructibility, due to technically being dead; However, the power of objects such as the Golden Weapons was sufficient enough to ultimately destroy their forms. Nevertheless, due to being undead, the Skulkin had no need to eat, sleep, etc., though some members still desired the luxuries that came as a result of these needs. Likewise, their undead status left several of them mute, although some were able to get past this disability, most notably the higher-ranking members.
Additionally, Skulkin had the ability to split their bones apart and have their parts act independently of each other, allowing them to attack unsuspecting opponents and giving them a key advantage in combat. Likewise, their origins as fallen warriors ensured every Skulkin at least some prowess and experience in combat, although the level of skill would vary. Following their alliance with Garmadon, several members were also taught Spinjitzu, though with varying skills and results. Consequently, they rarely used the power during combat due to their lack of skill.
- Main article: Skulkin Vehicles
- The word "Skulkin" seems to be a play on "skulking," which means "[keeping] out of sight, typically with a sinister or cowardly motive." The Skulkin, led by Garmadon, were indeed preparing in the Underworld for around a decade for Garmadon's sinister plan to steal the Golden Weapons, unbeknownst to the general population of Ninjago. They are also disgraced warriors, which implies they were cowardly and dishonorable in their lifetimes. The name is also based on the word skull.
- The name was not officially approved, explaining why it was not originally spoken in the show, but it ended up being used in some places anyway. Another possible name was "Craniax."
- While Kruncha, Nuckal and Wyplash are never explicitly called generals in the TV series, their higher status is implied such as when Krazi calls Wyplash "boss" in "Return to the Fire Temple."
- Though the cards indicate they have Elemental Powers, this is not canon to the show.
- There are many instances of Skulkin having the wrong armor or loincloth color:
- Samukai's appearance from the LEGO.com website is incorrectly colored blue instead of red.
- In some images, Wyplash's armor has gray spikes instead of white ones.
- Chopov's armor spike changes color from time to time in the sets (sometimes gray and sometimes red).
- Samukai and Chopov's torsos were switched in the group images for 2505 Garmadon's Dark Fortress.
- Samukai does not have armor due to his abnormal design, while Nuckal, despite being a General, has the same blue warrior armor as Krazi. This means that while the warrior armor has four color variants, the general armor only has two, those being gray and white.
- Skulkin appear many times after the pilots, though mostly as small cameos. After Lord Garmadon breaks his ties with them in "Darkness Shall Rise," they appear only once more in "All of Nothing." It would appear that the Skulkin were mostly written out of the series after that, leaving only Kruncha and Nuckal left.
- The identity of the Skulkin and their role was left ambiguous until Tommy Andreasen commented on the significance of the Underworld in 2016:
- According to the 2011 edition of the Ninjago website, the Underworld is the fate of all living things, implying they make up all of Ninjago's deceased. In the Official Guide, though, the Underworld is said to be where those who long to conquer Ninjago are sent.
- However, in Possession, it's established that the Cursed Realm is where the wicked go, once again leaving their roles in question.
- Finally, in 2016, Tommy Andreasen confirmed the Underworld is only for warriors who were disgraced in battle, explaining why all Skulkin are generally adequate and good fighters.
- The Ninjago website museum gave a slightly different explanation, stating "The Underworld is the realm of the dead, populated by fallen warriors who have never fully realized or accepted their passing."
- In the show, the Skulkin generals acted noticeably more comedic than in their depictions in other supplementary materials, presumably as both comedy and to highlight the roles of Samukai and Garmadon as antagonists.
- The character designs of the warriors (Frakjaw, Krazi, Chopov, and Bonezai) were used to make generic soldiers in the TV series, appearing multiple times within the same shots, which would be seen again with the Serpentine. Bonezai's design was used to make generic soldiers in the LEGO Battles: Ninjago game.
- Clouse may have taken control of the Underworld following his banishment.
- Their appearances are similar to Calaca from Central American culture.
- With the release of Ninjago: Legacy sets, the Skulkin were released in LEGO sets for the first time since "Day of the Departed."
- The Skulkin with abnormal head shapes may have been an early evolution of human when they were alive.
- Tommy Andreasen most commonly spells the word as "Skullkin," as seen on his Twitter and in his non-canon novel Way of the Departed. It was also spelled this way in the Hageman Brothers' original script for the pilot episodes.
- The skeleton figurehead is the only Skulkin not to have glowing red eyes in his eye sockets.
- The Skulkin have a similar appearance to Re-Awakened, another Skeleton Army.
- Samukai is the only Skulkin known to have died twice, first as a human and again as a Skulkin.
- They were referred to as "Skeleton Warriors" in an older version of LEGO.com.
- The warriors' faces resemble those of the Skeleton Warriors from LEGO's Castle (2007) theme.
- It's unknown whether they retain memories from their previous lives.
- One possible evidence supporting this is the fact that Samukai was a ruthless warrior leader in his human years according to Way of the Departed (though the novel is not officially canon). This would explain why he became the king of the Underworld.
- As of Tales from the Monastery of Spinjitzu, Legacy Wyplash's minifigure is used as the generic Skulkin design in the TV series.
- Ninjago Wildlife
- "An Underworldly Takeover