Elena is a brunette with short black hair.
In the live-action film, she wore a red jacket.
In Ultimate Alien, she wears a lab coat while working in her father's lab. When she is not working, she wears a black dress and a perl necklace. She also puts earrings and has puckered lips.
In her Nanochips form, she is ten feet taller and her body is black with blue stripes. She no longer has pupils and her eyes are much larger. She also has horns on the top of her head similarly to that of Aku or Maleficent and she speaks in an ominous voice.
According to Gwen, Elena was Ben's first crush. She helped Ben joining the soccer team when he was 3 and used to be best friends with him and Gwen. While this was happening, her father Victor Validus had been studying the Nanochips for years and eventually becomes overtaken by his work. Upon realizing he's been infected by the Decoy Queen, Victor tries to warn Max about "The Hive". However, Max believes that Victor was stealing from him and orders him and Elena to leave Bellwood immediately. Ben and Gwen were saddened when Elena left, so Max chose never to tell them why they moved away.
Elena first appeared in the live-action film, Ben 10: Alien Swarm, when her father was kidnapped and used as a Hive for the chips. She tries to attract attention by organizing an illegal trade on the black market, hoping the Plumbers will catch her and she'll be able to explain. Kevin Levin posed as the buyer, with Ben and Gwen as his partners. Elena reveals herself to the trio asking for help and Ben agrees, when suddenly the chips come to life and attack them. Kevin suspects that Elena set them up, but Elena insists that she had nothing to do with it. Elena mysteriously disappears during the team's battle against the Nanochips, which arrived Kevin's suspicion even more. Later, Elena follows them to Plumbers HQ but Max catches her and kicks her out.
The next day, Ben runs into Elena while she was riding her motorcycle and accompanies her to her father's lab. As they investigate the remains of Victor's research, Bellwood Citizens attack them while under the influence of the chips. They manage to escape when Ben launches a pulse feedback onto the victims. They then find Gwen and Kevin running from a giant Nanochip mace. Ben transforms into Humongousaure and destroys the mace, demolishing Kevin's car in the process. The four return to Plumbers HQ where Max is receiving reports about victims all over the world. He wasn't happy to see Elena at first, but later realizes that Validus may have been right all along and allows her to help. Unfortunately, Max becomes possessed by one of the chips and escapes. Without Max, the team discovers that the Nanochips are being mass produced at a factory in Missouri. They all travel to Missouri in the new car Kevin got Ben as an early birthday present and sneak into the factory. There, the team discovers that the Queen is inside Victor's body using him as a Hive to mass produce the chips. Elena admits to have known her father was being used as The Hive all along, but she didn't say anything fearing they wouldn't believe her (just like how the Plumbers didn't believe her father). While Gwen and Kevin consider sacrificing Victor to save the world, Ben and Elena are against it. Instead, Ben using his newest transformation, Nanomech, to enter Victor's body and destroys the Queen. Without the Queen, The Hive dies freeing their victims and ending their threat. Elena is last seen walking together peacefully with Ben's Team, teasing Gwen on how she earned her place in their team.
Elena reappears in the Ultimate Alien episode, Revenge of the Swarm. It is revealed that her father died and she usurped his research in studying the Nanochips, even creating a forcefield barrier to prevent them from escaping. When Ben shows her the chip that was part of the swarm that attacked him last night, Elena lies saying it isn't hers. Later, she finds the team inspecting her father's grave in the cemetery and agrees to help them in resolving the mystery saying that their situation is far more important than work. However, when the chips kidnap Julie, Ben grows suspicious of Elena and eventually discovers that she is the one siccing them on others so she can have him to herself. This is proven further when Elena transforms into a Nanochip hybrid, revealing that the Nanochips possessed her into becoming their new Queen whereas the one destroyed by Nanomech was a decoy. She defeats Armadrillo by choking him with Nanochips, but Julie breaks free of her bonds and appeals to Elena's inner goodness convincing her to stop. Elena agrees and sacrifices herself to destroy The Hive once and for all, but later the Nanochips begin to reform hinting some life left in them.
In The Perfect Gilfriend, Elena is revealed to have survived her attempted suicide. When Julie goes away for a tennis tournament, Elena impersonates her identity to be with Ben without him knowing it's really her. In her Julie form, she does whatever it takes to please Ben and even lets him stay home and watch Sumo Slammers while she goes shopping with Gwen. Elena also decides to eliminates everyone else around so no one will suspect her, such as pushing Gwen off of an elevator shaft (albeit she survived the fall) and bringing to life Evil Buildings to kill Kevin (unaware he was rescued by Ben as Way Big). Despite all these actions taking place whenever "Julie" is around, Ben remains unaware of her true identity until he sees a replay of Julie's tennis tournament from yesterday. At this point, Elena finally reveals herself to Ben much to his horror and disapproval. Things get worse when the real Julie returns from the trip, provoking Elena to transform into her Nanochips form again and defeats Ultimate Echo Echo by choking him with Nanochips again. However, Julie reminds Elena that she kills Ben then no one will have him. Elena eventually escapes through the sewers proclaiming: "[She] now knows hate is like!".
Powers and Abilities
In the live-action, Elena demonstrated an expertise in hand-to-hand physical combat during her battle against the Bellwood Citizens. She even broke a pipe with her bare hands and used it to fight them.
In her Nanochips form, she has the ability to control Nanochips at will and shape-shift into anything she wants. She can also use her Nanochips to control and manipulate technology, such as stopping the elevator before it crushes Spidermonkey and bringing buildings to life. She also has a claw she can pick stuff with.