|“You were built to protect those who cannot protect themselves.”|
|— Dr. Julien to Zane|
Dr. Julien was an inventor who created several impressive robots, including Echo Zane, the Falcon, the Juggernaut, and most notably, his son Zane, who is also the Elemental Master of Ice and the first Nindroid. Julien took care of Zane in the years following his creation, before erasing his memory shortly before passing away. However, Samukai resurrected Julien, using him to build vehicles for the Skulkin army. For much of his life, Julien was imprisoned inside a lonely lighthouse, which was guarded by a colossal sea creature—the Leviathan.
Shortly before the final battle, the Ninja journeyed to the lighthouse prison, where Zane reunited with his father. With the Ninjas' help, Julien escaped the lighthouse due to Zane freeing the Leviathan, allowing it to escape as well. Julien would go on to create several vehicles for the Ninja, including the Earth Driller and Fire Mech, all while bonding with his son. Unfortunately, Julien had trouble keeping up with the Ninja, and stayed behind when they went to the edge of the Dark Island to combat the Overlord. Aspiring to make himself useful, Julien flew the Bounty to the scene of the battle, using the ship to block a missile that would've harmed Lloyd, Wu, and Misako. After leaving the Dark Island and returning to Ninjago City, Julien witnessed the final battle between Lloyd and the Overlord, and after Lloyd won, Julien rejoiced with everyone else.
Following the final battle, Dr. Julien passed away, but his work influenced Cyrus Borg to develop a new series of Nindroids. Yet Julien's image would be tarnished when the Overlord corrupted the Nindroids and used them to his will. At the end of the conflict between the Ninja and the Nindroids, Zane sacrificed himself to defeat the Overlord, with his original body being destroyed in the process. Despite this, the rogue Nindroids were destroyed. At one point in time, a statue of Julien was erected in Birchwood Forest. On the Day of the Departed, Zane commemorated Julien at his statue. Meanwhile, Cole accidentally revived the Ninjas' old enemies, including the corrupt Nindroid Cryptor, who attacked Zane and destroyed Julien's statue. Once more, Zane defeated Cryptor, preserving his father's image as a trailblazing inventor.
Dr. Julien created Zane in his Hidden Workshop. As time passed, he taught Zane how to walk, speak, and perform other basic human activities, such as cooking and housekeeping. He also built the Falcon to serve as a companion for his creation.
One night, an ill old man came to the workshop, and Dr. Julien took him in. The next morning after the old man left, he is visited by a man named Wu. Wu states he is looking for Zane, and Julien proceeds to lead Wu to him. He then mentions that it was as if winter followed the old man, and that his son was acting peculiar after he left.
Eventually, Dr. Julien's health began to fail as he grew old. On his death bed, he told Zane "The only reason I'm about to do this is because I love you", before turning off his memory switch, making Zane forget about his past. But very soon after his passing, he was resurrected by an elixir of Samukai, whom demanded that he build weapons for the Skeleton Army. Julien refused, but was forced to after he was kidnapped by them and placed on a lighthouse guarded by a tentacled beast. He was told if he did not comply, he would never see his son again, and submitted to the Skeleton's demands.
During his time in imprisonment, he built a robot to keep himself company, also called Zane.
Later, Zane finds out he is a Nindroid and turns on his memory switch, and sees all of the time he spent with his creator. It appeared that he created Zane because he did not have a family of his own, and grew to love him as a son. Knowing this made Zane feel stronger, which helped him unlock his True Potential against the Treehorn Queen.
When the Ninja set sail in the broken Destiny's Bounty toward the Island of Darkness, Zane senses they are approaching an island before they crash onto the shore. They get off to investigate and spot a tall tower, with Zane calling it a prison. Dr. Julien opens the door excitedly upon seeing them, happily greeting his son and rushing them inside after mentioning an unspoken of threat outside.
Dr. Julien barricades the front door and looks around the island through a small camera, and after announcing that it is safe, he escorts them upstairs. He tells his guests to take a seat and sends a small robot to hand out cups, pouring tea for them afterward.
Zane spots his blueprints and questions how his father could be alive. Dr. Julien tells him that once he had passed away, Samukai revived him with a special elixir, called Resurrectea, commanding him to make the Skulkin war machines. Although he refused at first, Samukai stranded him on an island in the prison and placed the Leviathan as guard, telling him that he would be able to see Zane again if he complied. Dr. Julien says that he wanted to see his son again, but was afraid that Zane would think he was a monster for creating the Skulkin machines.
Zane promises him that he will figure out a way off the island, and Jay asks if Dr. Julien could repair the Destiny's Bounty. He tells them that he would have the Bounty repaired by dawn, but once they hear the growling of the Leviathan, Dr. Julien orders the Ninja to hide. The Leviathan looks into the prison, and after seeing that everything is normal, leaves.
After they work on the repairs until nightfall and have dinner, Zane asks his father if he could make an adjustment in himself to remove his memory switch. Dr. Julien assures him that he is perfect the way he is, though Zane says that he likes his life and would not want to forget about him again. Dr. Julien tells him that neither of them will forget and that he is glad Zane found him, and as they hug Zane replies saying that he is thankful that he was created.
The two suddenly hear the Leviathan approaching, and they quickly rush to the Bounty to inform the Ninja to escape. They all get on board, and as the Bounty begins taking flight, the Leviathan's tentacles grab onto the ship. Lloyd uses his powers in an attempt to release the monster's grip, which works temporarily before it grabs onto the ship again. Zane spots a chain attached to the creature and decides to unchain it. Despite his father's warnings, he jumps off the Bounty into the sea, swimming down where the Leviathan's chains remain and using the Starteeth to gnaw through the metal. Upon being released the monster stops attacking, and once Zane climbs back on the Bounty he explains that not even a monster deserves to be held captive.
As the Ninja are celebrating the restoration of their powers on the beach, Dr. Julien finishes the repairs on the Falcon, allowing it to fly again.
The Ninja return to the shore, Dr. Julien frantically questioning the sound of the horns in the distance. Master Wu explains to him that the Celestial Clock had reached zero and Lord Garmadon received the ultimate weapon, the Garmatron.
While the Ninja rush after Lord Garmadon, Dr. Julien requests to be left behind as he cannot keep up, assuring Zane that he will stay in the Destiny's Bounty before saying his farewells.
Later, as the Overlord uses the Garmatron to fire a missile at Lloyd, Dr. Julien arrives in the Destiny's Bounty and uses it to block the attack, abandoning the ship while it crashes.
On the shore of the Island of Darkness, Dr. Julien helps bandage Lloyd's broken leg. He tells Lloyd that it is broken, and will take time to mend back. Afterward, he follows the Falcon alongside the Ninja to the Temple of Light.
When the Ninja used their four Elemental Blades to reveal the Golden Mech, he explains that time has rusted, after eons of disuse, the machine, but Lloyd manages to reboot it as he is the next Spinjitzu Master.
With the Mech and the Ultra Dragon, the Ninja and Dr. Julien return to Ninjago. He, Master Wu and Misako witness the Final Battle between Lloyd and the Overlord on the Ultra Dragon.
Death and Legacy
Sometime after the Overlord was defeated, Dr. Julien died under unknown circumstances, presumably once again because of his old age.
Dr. Julien was revered as a great inventor and as the creator of the first Nindroid. Cyrus Borg would later praise his work, saying that he would have fit right in the modern New Ninjago City. Ultimately, his legacy in the Nindroids would be tarnished when the Overlord used Zane's blueprints to create General Cryptor and his Nindroid army. Fortunately, some time after the Overlord's defeat, a new faction of Nindroids were created to do good.
When Nya and Jay were trying to escape from Nadakhan and his crew, they take refuge at the Lighthouse Prison, where Julien was once imprisoned for many years. During this, they discover another, more primitive version of Zane they name Echo Zane, whom Julien built as a makeshift companion during his own imprisonment.
During the Day of the Departed, Zane returned to Birchwood Forest and constructed a statue of Dr. Julien in honor of him. The statue was then destroyed by Cryptor.
- He has the same hairstyle as Ed and Griffin Turner, though a white color.
- In "The Last Voyage," Dr. Julien told Zane that he never programmed him to cook, but in "Tick Tock," Zane's memories show them cooking a soup together (though likely, it's possible Zane picked it up as time went on).
- In "The Last Voyage," the prison tower Dr. Julien was imprisoned in is covered in "tally marks," indicating Julien spent an incredibly long amount of time trapped in the the Lighthouse.
- In Dark Island Trilogy, Part 3 Dr. Julien is seen in Wu's vision, along with Yang, and the Elemental Masters of Water and Fire.
- In the credits, he was called "Tinkerer."
- He does mention that he recognizes Wu in "The Last Voyage," despite them meeting for the first time in the flashback shown in "Snake Jaguar."
- It is more than likely that he died of old age.