|[List of appearances]|
- “The only reason I'm about to do this is because I love you.”
- ―Dr. Julien to Zane before turning his memory off.
Dr. Julien is a character of the Ninjago theme. He appeared in the Ninjago: Masters of Spinjitzu episode "Tick Tock". He was revived by Samukai after his death. He later dies permanently between the second and third seasons.
Dr. Julien is the inventor that built Zane and the Falcon. He spent most of his life with his "son" and he taught Zane to do many everyday things. When he was on his death bed, he told Zane he was made to protect those who cannot protect themselves and that he needed to move on to the next stage in life. Before he passed away, he switched off Zane's memory switch so he could not hurt Zane with loss. He also had a robot to protect their home from Treehorns, which is later destroyed by Zane, before he unlocks his full potential.
In the next season, it is revealed that he is still alive and held captive in a deserted jail in the middle of a vast sea. It turns out that shortly after his death, Samukai visited him and revived him with a potion, forcing him to build powerful machines that would aid him in attacking Ninjago. To avoid him escaping, Samukai chained a large sea creature at the bottom of the sea as a guard. He was found by the ninjas and was rescued in The Last Voyage. He has since aided and lived alongside them in the events leading to the final battle between Lloyd and the Overlord.
In the third season, it is revealed that he died from unknown reasons, and Zane secretly mourns losing him again. Cyrus Borg comforts him in hinting that he and his father knew each other and worked together.
- The Falcon
- Possibly the Juggernaut robot, as the Falcon and the robot have the same symbol
- The tree fortress, because his symbol is on the door
- The Skulkin's Battalion
- Cole's Earth Driller
- Kai's Fire Mech
- "You were built to protect those that cannot protect themselves..." - Dr. Julien to Zane
- "You were always the son I never had..." - Dr. Julien to Zane
- "And believe me when I say, I thought I was kaput!" - Dr. Julien to Zane
- "I may not be able to fight, but I can fly!" - Dr. Julien after blocking a missile with the Destiny's Bounty
- In his old age he looks very similar to Jay's father Ed. Another similarity is his love of inventing.
- He has the same hair as Ed Walker and Count Dooku's Clone Wars variant.
- In "The Last Voyage", he told Zane that he never taught him to cook, but in the flashbacks in "Tick Tock", he and Zane are shown making soup together.
- His name has been officially proven as Dr. Julien in LEGO Ninjago: Character Encyclopedia. His name was never mentioned on the TV show, until the end credits of later episodes involving him.