The Red Ninja and Master of Fire. Kai was once a blacksmith and owned a small shop with his sister Nya originally run by their late father. When the Skulkin Army took Nya hostage, Kai was forced to master Spinjitzu and eventually teamed up with the other Ninja to seek the four fabled weapons of Spinjitzu to stop Lord Garmadon.
The Blue Ninja and Master of Lightning. Jay was raised in a junkyard with his parents, Ed and Edna, whom he eventually abandoned and journeyed to Ninjago City to test his inventions, which ultimately failed. However, Sensei Wu saw the Lightning within him and trained him with Cole and Zane at the Monastery, eventually meeting Kai and joining forces to find the Golden Weapons of Spinjitzu. Being the fastest of the Ninja, he learns Spinjitzu at the Caves of Despair, and helps the others learn it as well. After foiling Garmadon's plans, he obtains the Nunchucks of Lightning and the Lightning Dragon, Wisp, both of which he keeps thereafter. Is one of the smartest technologically of the team, alongside Nya.
The Black Ninja and Master of Earth. He is the leader of the Ninja. Originally, Cole was a mountain climber testing his strength when Sensei Wu discovered he had the power to become a ninja, and brought him to the Monastery to train alongside Jay and Zane. Eventually, Sensei Wu brought the four ninja together and sent them on a quest to defeat the plans of his evil brother and to find the Golden Weapons of Spinjitzu. After finding and defeating Garmadon and rescuing the weapons, Cole acquired the first Golden Weapon, the Scythe of Quakes, along with the Earth Dragon Rocky. Strong and athletic, Cole often develops the Ninja's plan of attack against their foes.
Badass: There is a reason he's the leader of the four Ninja.
"Well Done, Son" Guy: What was holding him back from gaining his true potential was his father's approval.
Zane the White Ninja
The White Ninja and Master of Ice. Zane has no memory of his past or his parents, being a homeless orphan all his life. Sensei Wu found him "testing himself" underwater, however, and seeing the Ice within him, brought him to the Monastery to train with the others. After apprehending Lord Garmadon and defeating the Skulkin Army, he uses the Shurikens of Ice in battle and keeps the Ice Dragon, whom he names Shard. Gifted with a sixth sense, Zane appears to have the wisdom to tell the future, and is the wisest and stealthiest of the Ninja. However, his odd behavior and lack of humor makes him the target of the others' jokes, which Zane usually doesn't understand. But then something very stunning reveals the truth behind his past and personality. Zane discovers a workshop that holds blueprints of himself, proving he's actually an android. Afterwards, he remembers he had a father: a man who built him to be the son he never had. Unfortunately, Zane outlived him, but his father switched off all of his memory right before collapsing on his deathbed so he would never feel the pain of loss. Zane sheds a single tear and re-activates his memory- and unlocks his True Potential.
The childish son of Lord Garmadon who believes he is destined to follow in his father's footsteps as a dark alchemist overlord. Kicked out of his Boarding School for Bad Boys, Lloyd is shown to be immature and has a dire love for candy, as well as a former grudge against the Ninja for humiliating him. Lloyd wreaked havoc on Ninjago by releasing the Hypnobrai, Fangpyre and Anacondrai tribes, however each took advantage of his naive behavior and betrayed him, leaving him to be defeated by the Ninja. However, Sensei Wu, his only uncle, took pity on him and convinced him to fight against the Serpentine, which he accepts. He later becomes the Green Ninja, meaning he is prophesied to defeat his father, Lord Garmadon.
Dark and Troubled Past: Abandoned by his parents (not that they had any other choice) and thrown into a boarding school for kid villains, heavily bullied at said boarding school for not having the drive to commit actual evil, and trying to prove his worth, only to fall into Humiliation Conga over and over again. Luckily he met his uncle and the ninjas and he got better.
Determinator: Refuses to quit during the Final Battle, ultimately what unlocks his true power as the Ultimate Spinjitzu Master.
Golden Super Mode: When he realizes his true power during his battle with the Overlord.
Goo Goo Godlike: Being the Green Ninja he can use the all powers of the Golden Weapons, without touching them. He also used Spinjitzu on one his first tries. And he's only about 10. However, this is also somewhat problematic, as it means he can't control his true power just yet.
He finally masters his powers in "The Rise of the Spinjitzu Master", becoming the Gold Ninja and destroying the Overlord.
Spinjitzu Master of all elements. He uses the power of wisdom and creation, and mentors the Ninja to help them against their foes. He is the son of the first Spinjitzu master and brother to the evil Lord Garmadon.
Sister of Kai and the former owner of Four Weapons, Nya was held captive by Samukai on Lord Garmadon's orders, seeing her as a potential pawn in his conquest for power. She was finally rescued by her brother at the Fire Temple and awaited his return from the Underworld. She eventually moved in at the Monastery with the four Ninja, where she trained to perhaps become a future Master of Spinjitzu. Headstrong and courageous, she is determined to prove she can become a ninja and prove her brother wrong, so she adopted the mysterious persona of Samurai X, a high-tech crime-fighting samurai clad in red armor and uses a large robot as a means of transportation. She also has a mutual crush on Jay.
Gadgeteer Genius: Not only did she build her Samurai Mech and armor by herself in the spare time she had while the Ninja were on missions, she modifies the Ultra Sonic Raider to incorporate a detachable flight module, and later builds Kai his own Fire Mech.
It Is Pronounced Tro PAY: While never referenced in-series, her name is pronounced Nia as opposed to the more Japanese esque way.
Triang Relations: In Season 3, a love fortune machine tells her that her true love is not Jay but Cole. She tries to deny this at first, but she starts to have feelings towards Cole. He doesn't notice (yet), however.
A cocky kung-fu "Sensei" who allows the Ninja to train Lloyd at his Dojo, entitled "Dareth's Mojo Dojo." He is revealed to have lied about his kung-fu claims.
Dumbass Has a Point: Jay tries to use the fact that the Ninja saved the city from the Great Devourer as leverage to train at the Dojo, only for Dareth to point out that Garmadon's the one who actually defeated the Devourer.
Epic Fail: After seeing Lloyd easily destroy ten boards with an elemental chop, he attempts to do it himself with FIFTY boards. He barely has to hit it without screaming in pain.
The Load: His attempt at stopping the pirates only causes more problems for the Ninja and Lloyd is forced to save him.
In the season two finale he averts this by accidentally putting on the Helmet of Darkness, giving him control of the Stone Army.
He averts this again by saving the students from a shark attack.
Screw This, I'm Outta Here!: This is invoked during Season 3, where they casually leave the ninjas behind using jetpacks while nindroids ambush the scrapyard, though they did believe they could handle it. Jay asked for a jetpack, but they don't have one for him because he hardly visits them.
Zane's father, or rather, his creator
All There in the Manual: His name has never been revealed in the show, but is mentioned in the LEGO Ninjago Character Encyclopedia.
Back from the Dead: In "The Last Voyage", the Ninja find him on a prison tower in the middle of the ocean and learn that on his deathbed, he was revived by Samukai so he could design vehicles for the Skeleton Army.
Gadgeteer Genius: His achievements include Zane, the Falcon, and a guardian robot, all of which he built from a small workshop in the Birchwood Forest. Later, after being brought back from the dead, he helps design the vehicles for the Skeleton Army. After he is rescued he builds a Power Driller for Cole.
Lloyd Garmadon's mother and Lord Garmadon's former lover.
Never Mess with Granny: Vague Age notwithstanding, she has graying hair and looked about the same age as Lord Garmadon and Sensei Wu in Wu's photograph. And yet she is amazingly agile, knows Spinjitzu, and has more expertise on the prophecy of the Green Ninja than Sensei Wu himself.
Wrong Guy First: When looking at a picture of herself and Lord Garmadon when they were young, she tells Sensei Wu "I should have chosen you".
Fun with Acronyms: Her name stands for Primary Interactive X-Ternal Assistant Life-form.
The cunning and decisive ruler of the Underworld, Lord Garmadon was once the loving brother of Sensei Wu and the oldest son of the first Spinjitzu Master. When his father passed away, he swore to protect the Golden Weapons with his younger brother, but was consumed by greed and power. A battle at the Monastery broke out between Wu and Garmadon, who was banished to the Underworld where he assumed leadership of the undead legions. Vowing to return to collect the weapons and reshape Ninjago in his own evil image, Garmadon plotted many years in the shadows until finally he enacted his plan of world domination. He sent Samukai to the Surface World to collect the weapons, but Sensei Wu and the Ninja foiled his plans- or so it would seem.After uniting the weapons, Samukai was vaporized in a portal between space and time, which Garmadon escaped through to grow powerful enough to unite all the weapons. Now, Garmadon, hideously mutated with four arms, has returned from the portal to seek revenge on the ninja and his younger brother, however in an unexpected turn of events, he allies with them to stop the Serpentine. Despite his evil ways, Lord Garmadon has shown deep concern for his son and does not wish for him to follow his footsteps as a dark overlord.
Being Evil Sucks: Due to being evil due to it literally running through his veins, so he'll always be forced to be evil, but he's aware of this and doesn't truly want to be, particularly where his son is concerned. Gets worse when Lloyd is revealed to be The Chosen One.
Nominal Hero: The citizens of Ninjago City didn't hesitate to give Lord Garmadon credit for destroying the Great Devourer, never mind that he did it for revenge and kept the Four Weapons of Spinjitzu for his own purposes.
Papa Wolf: Very much so, he brought an entire army to protect his son. Even after he becomes the Big Bad again, he refuses to let any harm befall Lloyd.
After Pythor and the Overlord kidnap Lloyd, he goes against his vow of peace to fight them.
Villainous Breakdown: At the end of the Ninjaball Run, when the Ninja just won't quit and finally win the race, foiling his latest plot.
Woobie, Destroyer of Worlds: It's hard to deny that he's this. He was forcibly made evil thanks to being bitten by the Great Devourer and now has to fight his own son.
Yin-Yang Bomb: Combines his own dark power with the Golden Weapons to destroy the Great Devourer.
The four-armed King of the Underworld. He was defeated by Lord Garmadon when he was banished to the Underworld, causing him to step down and allow Garmadon to control the legions of the Underworld. Samukai leads the Skulkin Army in the Surface World of Ninjago, carrying out Garmadon's orders and seeking the Golden Weapons of Spinjtizu. Soon, Samukai possessed the four weapons and betrayed Garmadon, only to be vaporized by the power of the weapons combined. His choice of weapons are four bone daggers he uses because of a mutation that granted him four hands, making him superior to all skeletons.
Expy He is similar looking to General Grievous. He even has similar fighting moves and four arms.
Too Dumb to Live: He bites into a donut-shaped rock to see if it tastes like a donut. Good thing he's already dead.
Moreover, in the short story "The Choice", Zane manages to convince Nuckal that he was never there by telling him that Nuckal was just remembering a funny joke Samukai told him earlier. The fact that he actually thought Zane's joke was funny highlights his gullibility.
Dragon Ascendant: He planned on becoming the new leader of the Serpentine after Pythor is killed by the Great Devourer, but Lord Garmadon wins their trust before he does and leaves him with only the other Generals.
Monster Is a Mommy: Has a son in the time between the Overlord's defeat and his return in digital form.
Snake of Ice and Warrior for the Hypnobrai Tribe. When Lloyd stumbled upon the Hypnobrai, Slithraa attempted to mind control him but ended up controlling himself, thus allowing Lloyd to take over the Hypnobrai tribe, much to the dismay of the others. He was formerly general of the tribe, before Skales took his place after defeating him in the Slither Pit.
Put on a Bus: After Skales takes his place as leader, Slithraa begins appearing less frequently. "The Snake King" is the last episode he appears in before disappearing entirely, and that was only a cameo appearance on (appropriately enough) the Snake Bus.
The Fangpyre are a red-colored faction of the Serpentine. Their poisonous fangs can convert machines into living biomechanical snake-themed vehicles or mutate organic lifeforms into snakes. They are the second tribe to be released.
Snake General of Fire and commander of the Fangpyre Tribe.
Multiple Head Case: Like Fangtom above, though it's explained that his second head was caused by Fang-Suei biting him in the heat of battle thinking he was a desert slug.
The Anacondrai are a purple-colored faction of the Serpentine. They have the power to turn invisible. When they were locked away their was a lack of food so they turned cannibal until only Pythor was left. According to Skales they are the most feared tribe. They were the third tribe to be released.
Pythor P. Chumsworth
Last snake of the Anacondrai Tribe. Sensai Wu reveals Pythor is their most dangerous enemy yet. He plans to unite the five Serpentine tribes to find the four Silver Fang Blades and unleash the Great Devourer. He's ultimately eaten by the Great Devourer, but he later returns to free the Overlord from his digital prison.
Big Bad: While the five tribe leaders were on even footing at first, he eventually manipulated his way into this role in season 1.
The Constrictai are a black and orange-colored fraction of the Serpentine. They can dig underground to ambush their enemies, and have a fierce grip. They are the fourth tribe to be released.
Snake General of Earth and commander of the Constrictai Tribe.
Dumb Muscle: Obviously, compared to the other generals.
Snake of Earth and scout for the Constrictai Tribe.
Snake of Earth and trooper for the Constrictai Tribe.
Snake of Earth and warrior for the Constricati Tribe.
The Venomari are a green-colored cobra/viper-themed faction of the Serpentine. Their toxic venom can make anyone hallucinate. They are the fifth and final tribe to be released.
Snake General of the Venomari Tribe.
Extra Eyes: Most of the Venomari have four eyes, with the exception of Lasha, who appears to have lost a few.
Second in command for the Venomari Tribe.
Soldier for the Venomari Tribe.
Scout for the Venomari Tribe.
The Great Devourer
According to a legend, once all five Serpentine tribes unite, they will be able to find the four Silver Fang Blades and unleash the "Great Devourer". The Fang Blades are said to enhance the Devourer's abilities and make it unstoppable, releasing a terrible evil that will turn day into night. According to Sensei Wu, it will keep growing as long as it consumes. Garmadon was nice until he got bit by the Devourer as a child, turning him into the villain he is today.The Devourer slept under the Lost City of Ouroboros until Pythor put the Fang Blades into the statue of it and it rose out from underneath the city. It was destroyed by Lord Garmadon with the power of the Golden Weapons of Spinjitzu.
Attack Its Weak Point: Has one on the top of its head. Garmadon kills it by diving off the top of a building with all four Golden Weapons and attacking this weak point.
Hoist by His Own Petard: It bit Garmadon and turned him evil in the first place. It's ultimately Garmadon who destroys it.
It gets better: if Lord Garmadon hadn't become evil, he never would have sought the power to wield all four golden weapons. The only way to kill the Devourer? Strike its weak spot with all four golden weapons at once.
"Once, when the world of Ninjago was new, all things were bright and peaceful. Farmers toiled in their fields, in harmony with all the creatures of land, sea, and air. But in all things, there must be a balance. And so darkness crept upon the land, and came upon a lone snake in the grass."
What's especially ironic is that the Devourer itself is responsible for Lord Garmadon's Start of Darkness. Note also that the "darkness" responsible for the Great Devourer's transformation seems to be an incarnation of the Overlord.
The Overlord Army
An ancient evil from Ninjago's past that fought with the first Spinjitzu master in the past. He helps Lord Garmadon turn Ninjago into his own image, but later betrayed him and took over his body. His body is ultimately destroyed by Lloyd in the Final Battle with him, but he now lives on as an evil AI.
As Long as There Is Evil: During the final battle, he gives a speech, saying 'as long as there is light, there must always be shadow,' implying he's this trope. Considering having a massive explosion go off INSIDE HIM and destroy his physical form wasn't enough to kill him (though it probably would've put him out of commission for a good while had Cyrus not accidentally resurrected him), he probably has a point.
Badass: The only reason Lloyd managed to stand any chance at all in their first fight was because Garmadon was Fighting from the Inside, and even then, the Overlord beat him and left him with an injured leg. Even after Lloyd obtains his Golden Super Mode, the Overlord is able to fight him fairly evenly.
Big "NO!": Gives a series of them upon realizing Lloyd is about to destroy him.
The Corrupter: His Dark Matter has the ability to turn whatever it touches evil. He also makes Garmadon worse and worse through his manipulations. He's also the being responsible for creating the Great Devourer and thus turning Garmadon evil in the first place.
Devour the Dragon: The Overlord eventually betrays Lord Garmadon and possesses his body.
Knight of Cerebus: Is about the only villain in the entire series (at least the only one with a mind of its own) with absolutely no comical traits at all, and the leader of an army of Nigh Invulnerable soldiers at his command.
Idiot Ball: Usually a relatively adept manipulator, he sometimes fails to see the easier option when caught up in his own schemes. He insists on reclaiming his original body. As his computerized state potentially grants him whatever body or even bodies he wants, this is probably a case of this trope.
Of course, since he requires electricity to function in his digital state, and the ninja have the Technoblades, which are capable of stopping, and perhaps even destroying, him while he remains in the system, he may have a valid point for regaining corporeal form. He also wants to skip finding a host that can fight from the inside this time.
The process would also have the benefit of making him even more powerful.
Manipulative Bastard: Manipulated Garmadon into think he was the Big Bad, so he'd complete his ultimate weapon and disrupt the balance between good and evil, freeing the Overlord from his prison.
One-Winged Angel: After taking over Garmadon's body, he takes the form of a gigantic black dragon.
Pyrrhic Victory: He manages to escape the digital realm, but is unable to drain all of Lloyd's power and can barely keep his new body together.
Satan: Pretty much the Ninjago version anyway. Is it any wonder he turns into a dragon for the final battle?
Sealed Evil in a Can: The Overlord and the evil side of Ninjago which he inhabited were supposed to remain disappeared for as long as the balance between good and evil remained in check. However, Lord Garmadon's ambition to remake Ninjago in his image upsets that balance.
Due to losing his body in the final battle with Lloyd, his soul is stuck in machines, and while that gives him a lot of stuff to control he still wants a new body instead of being stuck in a computer.
This Cannot Be!: Is left in disbelief when Lloyd begins to fight back against him, unable to believe a mere human could manage to match him.
Ultimate Evil: Spends most of his screen time a disembodied voice considered to be the most evil entity in the entire series. When he finally appears in person, he's as frightening and powerful as he was made out to be.
The General of the Stone Army created by the Overlord and Lord Garmadon's personal translator.
Sealed Evil in a Can: Were sealed underground with the defeat of the Overlord, but unleashed by the Serpentine accidentally unearthing them.
The owner and the one who helped rebuild Ninjago city into New Ninjago City. being force to work with the Overlord he was the one who gave the ninja the technoblades before the overlord decide to FIX that....
Mini Mook: One Nindroid is much smaller than the rest (apparently due to a lack of material). He is appropriately nicknamed Mindroid.
An evil species of shapeshifters from the Underworld that serve as the antagonists of the second graphic novel (Mask of the Sensei).
Bluff the Impostor: One of the shapeshifters impersonates Sensei Wu, but Zane, Jay, and Cole realize their Sensei is a fake when Cole asks if he wants a cup of tea. The real Sensei Wu would of course agree; the shapeshifter who took his place claims to hate tea.
Master of Disguise: The shapeshifters can mimic anyone from the memories of those they encounter.
No Name Given: The species is so old that its name has been lost to history.
Sealed Evil in a Can: One of the important functions of the Skeleton Army was to keep these monsters from escaping the Underworld and entering Ninjago. Then Lord Garmadon sent the Skeleton Army to attack Ninjago instead. Oops.