|Residence|| Denver (formerly)|
|Age|| 15 (Alien Force)|
16 (Ultimate Alien and Omniverse)
|Affiliations|| Ben's Team (occasionally)|
Flame Keepers' Circle (formerly)
|Powers and Abilities|
|Relatives|| Unnamed mother|
Mr. Yamamoto (father)
|Alias|| Ben's Ex-Girlfriend|
Home Town Sweetheart (Carl Nesmith)
My Girl (Goop)
|Voice Actor||Vyvan Pham|
|First Appearance||Ben 10 Returns: Part 1|
Julie Yamamoto is Ben's ex-girlfriend and now friend. She first appeared in Ben 10 Returns: Part 1 at Ben's soccer game to congratulate him on his game-winning goalie work. She later broke up with Ben some time between The Ultimate Enemy: Part 2 and Rules of Engagement.
Julie has black hair, brown eyes, and wears a black t-shirt, mostly hidden under a pink hooded jacket and a white mini skirt. When playing tennis, she wears white wristbands, a white t-shirt, and her skirt. She has short black hair and sports white tennis shoes.
In Inspector 13, she is wearing a light blue vest with a dark blue skirt, black leggings, blue socks and her usual shoes.
In Omniverse, Julie looks similar to her Alien Force/Ultimate Alien appearance, except now she has a white t-shirt instead of a black one. She still has her old pink jacket, but now with light orange, yellow, and white stripes on it. She also now has longer hair in pigtails and there are thin black lines across her skirt. She also has long socks with orange and yellow stripes that go up to her knees. Her face now shows more Japanese traits than before.
Powers and Abilities
Being an ordinary human, Julie doesn't possess any superpowers herself, although she's quite good at tennis, and shows some fighting ability in Pet Project where she takes one of the Forever Knights electric maces and easily knocks out several Forever Knights with them (one of these knights being comically unintentional while she replied to Gwen's acknowledgment). Julie is the only one who can fully command Ship, making her a competent ally.
In Vreedle, Vreedle, Ship reveals that he can "merge" with Julie. When Ship enveloped her, he became a armored battle suit. In the suit, she demonstrates enhanced strength and great damage resistance, as well as the ability to fire powerful lasers.
In Eye of the Beholder, it turns out that Julie can understand Ship's language.
Alien ForcePier Pressure, Ben asked Julie out on a date. It was interrupted by Ship, who kidnapped Julie. During a rescue attempt, Julie found out about the Omnitrix, which she finds cool. In the end, it was revealed that Ship was trying to lead Ben to Baz-El, whose ship crashed and was about to explode. Ben and Julie helped fix Baz-El's ship and he left Ship with them, saying that he and Ben have a bond. On the walk home, Ship takes off after a passing truck, and Ben and Julie walk home, holding hands.
In Save the Last Dance, when Big Chill takes control of Ben's personality and starts eating every metal object in sight, Julie follows him on her motor scooter and alerts Gwen and Kevin. She also told them where Ben is headed. Gwen and Kevin manage to subdue Big Chill, only to discover that Big Chill was building a nest for eggs he had laid. The eggs hatch into baby Necrofriggians, and Kevin teases Ben about being a "mommy". As Julie takes Ben home on her motor scooter, she tells Ben that she thought he made a great "mom". Ben also stated that she gets straight A's.
In Pet Project it was revealed that Julie is keeping Ship as a pet; it put a strain on her relationship with Ben, as he feared Ship could do something that she couldn't handle. The Forever Knights kidnapped Ship, planning to use him to mass-produce spaceships to go to the Dragon's planet, brainwashing him. Julie managed to get through to Ship and bring him back to his senses. At the same time, she told Ben he wasn't the only one who saw Brainstealers From Outer Space; he skipped a date to watch a marathon of it. Julie would allow Ben and the others to use Ship's new spaceship form if they asked her.
In War of the Worlds: Part 1, Julie helped Ben fight against the Highbreed invasion and it turned out that she apparently had a curfew. She also seems to show a deal of concern and care for Ben. At the end of War of the Worlds: Part 2, Ben and Julie get close to kissing, but decided against it, as Gwen, Kevin, and Max were all watching. Ben then tells her that he will walk her to school the next day, and Julie gets home by riding Ship after giving Ben a loving smile.
In Vreedle, Vreedle, the Vreedle Brothers, hired by Baz-El to return Ship to him. As Julie refused, the Vreedle Brothers started being more aggressive, and Ben and Kevin go in court to claim their right on Ship against Baz-El, while Gwen stayed on Earth to keep Julie and Ship safe. When the Vreedle Brothers came back, Ship revealed he can "merge" with Julie, giving her a powerful battle suit she can use to fight back against the Vreedle Brothers. Ben is eventually able to get the judge's favor, and Baz-El reluctantly accepts that Ship is now Julie's.
In Singlehanded, Julie finds Ben's detached hand and takes it to Gwen and Kevin. She later uses Diamondhead's hand to fight Sunder. During the fight, Gwen helped her keep Ben's hand away from Sunder but Julie wound up being used in a trade when Sunder caught her. After Sunder was knocked out, she, under Kevin's instructions, held a beam on Ben's arm while they used Sunder's axe to put Ben back in one piece and unknowingly sent Sunder to the Null Void as a result.
In the The Final Battle: Part 1, Julie is briefly seen playing with Ship.
In Fame, sixteen year old Julie comforted Ben when his identity was revealed to the world. When he thought everybody would hate him, she kissed him on the cheek and told him that not everybody hated him.
In Duped, Julie becomes very upset with Ben not spending time with her, as he chose to watch the movie version of "Sumo Slammers" as his real self while leaving an immature version of himself with her.
In Hero Time, Julie becomes jealous of Jennifer Nocturne after she kissed Ben when he saved her life. Later, she was kidnapped by Overlord. When he tried to kill her and Jennifer, Goop saved Julie. Goop then called her "his girl", and she smiles. She then assisted in taking down Overlord.
As shown in Eye of the Beholder, Julie and Ben were going through relationship troubles. Ben apologized to Julie for being such a jerk and he promised to try to be a better boyfriend, which makes them both happy.
In Revenge of the Swarm, when Ben and Julie arranged a date, she was kidnapped by the Nanochips at the behest of Elena, who was jealous of her. When Armodrillo freed Julie, Elena used the swarm in an attempt to suffocate Armodrillo. Julie was able to convince Elena to stop her Nanochip activity if she really loves Ben, as well as Julie herself loves him. Then she watches Elena kill herself to stop the Nanochips and Ben's life is saved. As Ben mourned Elena's supposed death, Julie gave him some comfort before they both drove home in Ben's car.
In Greetings from Techadon, Julie and Ben competed in a golf course and Ben won, thanks to Brainstorm, but Julie was shown not to be happy and accused Ben of cheating in the death hole. At the end of the episode, Ben said he must go and have a rematch as promised to Julie.
In The Flame Keepers' Circle, Julie joins a philanthropic organization called the Flame Keepers' Circle, as she accepts their theology of using Diagon's technology to advance Earth's humanitarian efforts and create a utopia. She tries to get Ben and Kevin to understand but fails, becoming quite angry at Ben for this as he laughed in the Cult Leader's face and he himself uses alien technology to protect Earth. She believed this to the point of pretending to be a hostage for Conduit Edwards to make Ben revert from Big Chill. She again tries to preach the benefits of the Flame Keepers' Circle to Ben, but realizes her mistake when Ben tells her that it is Vilgax. She maintains a belief that alien technology should not be kept from humans although is far less fanatical.
In The Perfect Girlfriend, Julie went off to Europe for a tennis tournament, during that time Elena impersonated Julie to try and win Ben's heart. Right after Elena revealed herself, Julie arrived at Ben's home, and was able to talk Elena down again, prompting her to leave swearing revenge.
In The Ultimate Enemy: Part 2, Julie showed up after Ben stripped Vilgax of Diagon's powers and managed to talk him out of selfishly wiping out all evil. After Ben turned all of humanity back to normal, Julie kissed Ben on the lips for the first time in front of the others.
Julie appeared in Rules of Engagement with her new boyfriend and Ship. They are kidnapped along with Ester and Rook by Princess Looma. Julie fought Looma and with the help of Ball Weevil and Ship, she won. Ben and Julie then made an agreement to be friends after the break-up.
She later appears in The Most Dangerous Game Show as one of the females chosen to compete for Ben's hand in marriage. She is utterly uninterested in the contest, texting Hervé for the duration. This causes her to get knocked into the water during the "hole in the wall" round. After being sent to the Null Void with the other losers, she is later freed and returned to Earth.
Ben 10: Alien Force
- Ben 10 Returns: Part 1 (first appearance)
- Pier Pressure
- Good Copy, Bad Copy
- Save the Last Dance
- Pet Project
- War of the Worlds: Part 1
- War of the Worlds: Part 2
- Vreedle, Vreedle
- The Final Battle: Part 1
Ben 10: Ultimate Alien
- Fame (first re-appearance)
- Hero Time
- Absolute Power: Part 2
- Eye of the Beholder
- Revenge of the Swarm
- Greetings from Techadon
- The Flame Keepers' Circle
- The Perfect Girlfriend
- Inspector 13
- Night of the Living Nightmare (dream)
- The Ultimate Enemy: Part 1
- The Ultimate Enemy: Part 2
Ben 10: Omniverse
- According to Dwayne McDuffie, Julie's family is from Denver.
- It was revealed in Rules of Engagement that Julie doesn't like Mr. Smoothy.
- Julie owns a motorized scooter.
- Gwen considers that Julie is the "only one who has common sense among the four of [them]," as she always avoids trouble in every situation.
- Like Ben, Julie likes chili fries.
- Yamamoto in Japanese means 'one who lives in the mountains’ or ‘at the foot of the mountain’, this is one of the ten most common surnames; it is found predominantly in central and west-central Japan.
- Ben accidentally broke up with her over the phone while playing a video game of Sumo Slammers. Julie had believed that Ben's rude comments towards a game character were directed towards her instead.