Gwen Tennyson (Classic)/Ultimate Alien

In Hit 'Em Where They Live, Zombozo and other villains, including Vulkanus and Charmcaster, teamed up to take revenge on the Tennysons and company, and kidnapped Ben's mother Sandra. Enraged, Gwen released her dormant, inner Anodite for the first time since War of the Worlds: Part 2. Whilst Zombozo trembled with fear, Gwen began to grow to a huge height, promising that if one of his teammates (or other notable villains) even bumped into their families on the street, she would come for them. Petrified, Zombozo screamed off-screen and Gwen saved Sandra. When Kevin asked what happened to Zombozo, she simply replied "We came to an understanding" whilst smiling.
In Video Games, she tried out for her driver's license, earning it in the end.
In the episode Hero Time, Gwen became very jealous when Jennifer Nocturne started flirting with Kevin after he saved her life from Carl Nesmith. Kevin also protected Jennifer a lot over the course of the episode.
During her attempt to recover the first part of the Map of Infinity in the episode of the same name, she discovered it but was hit by a poison dart and ended up fainting, allowing Aggregor to catch the first fragment, but Kevin and Ben save her from near death.
In Reflected Glory, Gwen was comprehensive with JT and Cash. Gwen had the idea to use a mirror against the R.E.Ds, and her powers apparently did not greatly affect the R.E.Ds.
In Deep, the group went to the planet Piscciss to help Magister Pyke stop Aggregor. Gwen was caught by a squid-like creature, but Kevin revealed that he installed neuro-shock pulsers which could shoot lightning, allowing Gwen to get free. When they reached the nucleus of the planet Piscciss, an earthquake occurred. Gwen put an energy shield around them, but failed to protect Magister Pyke, so she stayed with him while Kevin and Ben went after the second part of the Map of Infinity. However, Aggregor arrived first and fled with the second part of the map after defeating Ben and Kevin. When the planet began to crumble, Ben as Goop saved the planet, re-constructing the lost water particles using Goop's Anti-Gravity Projector. At the end of the episode, Gwen consoled Kevin for having to leave the Blowfish in Piscciss.
In Where the Magic Happens, Gwen relied on Charmcaster to help her, Ben and Kevin survive traveling through Legerdomain to find the next piece of the Map of Infinity, the Alpha Rune. Along the way, she learned of Charmcaster's background and came to sympathize with her nemesis.
In The Forge of Creation, Gwen travelled with Ben and Kevin to stop Aggregor from absorbing a baby Celestialsapien's powers. Young Ben came along as Ben accidentally fell into the Chronal Randomization Barrier. Gwen, Kevin, and even Ben became annoyed with Young Ben. However, everyone eventually understood why Young Ben is so arrogant and cocky. He explained that, when dealing with the pressure and the danger that could kill somebody, he tends to joke around so he can be prepared to face anything. Unfortunately, everyone was easily defeated by Aggregor, who seemed to have won, but Kevin absorbed the immense energy of the Ultimatrix as a last resort, defeating him but becoming insane in the process.
In ...Nor Iron Bars a Cage, Gwen and Ben travelled to the Null Void Incarcecon to warn the warden about Kevin. The warden would have been killed if it were not for Gwen, (who saved him from crash landing using a much stronger version of the "Turbo" spell.) Ben implied Kevin needed to be "put down", which shocked Gwen.
In The Enemy of My Enemy, Ben and Gwen were shown to be having difficulties. The two argued about Kevin while trying to locate a ship. On the way, they stumbled upon Argit, who needed a place to hide from Kevin. They travelled to the Plumbers' Academy in the Rustbucket 3, only to be attacked by Kevin. They barely succeeded in defeating him, and Gwen said she turned the air lock on to send Kevin falling because she understood he would kill them if he had the chance. After Argit preformed his orders, Kevin attacked the Plumbers' Academy. Ben used Ultimate Echo Echo to deal with the nuclear bomb, while Kevin relentlessly attacked Argit. Gwen begged him to stop and to give himself up, but he knocked her down. Gwen remained there crying as Kevin stated that she was only spared because of what she used to mean to him. Ben returned and the two had a conversation. Gwen said that they could still help Kevin, Ben replied that they cannot.
In Absolute Power, Gwen was more determined than ever to save Kevin. Ben disagreed with Gwen, opting to kill him now rather than a last resort. Gwen went to Max, hoping he would disagree about killing Kevin, but her grandfather confirmed that killing Kevin was the right decision. He also told Gwen that if she disagreed, she should leave Ben to do it and not get in the way. Gwen left, disappointed and angry, ready to take desperate measures as she went to Michael Morningstar for help. Meanwhile, Ben went off looking for Kevin, who was relentlessly going after anyone he thought had betrayed him. Gwen stopped Ben from harming Vulkanus, accompanied by Michael. Ben was infuriated by Gwen's alliance, but she made a deal with Ben, saying that if her plan did not work, she would not bother him anymore. Gwen also admitted that she promised Michael enough mana in return for his help that would keep him at full strength and power for one year, furthering Ben's anger toward her.
Michael explained that he saved a part of the Dominus Librium, which could be used to turn Kevin back to normal. However, the machines and energy required to power it was only available at Los Soledad. In order to lead Kevin there, they needed bait. Gwen suggested herself. Gwen went to Total Zone and confronted Kevin. He admitted that he had been avoiding her so he would not absorb her energy, which he was desperately hungry for. They fought intensely, and Gwen tried talking some sense into Kevin. Unfortunately, this didn't work, and Kevin grabbed a hold of Gwen and absorbed both her magical and Anodite powers, making her scream in pain. Gwen retaliated with a blast and escaped.
Michael and Ben travelled with Gwen in the Rustbucket 3 to Los Soledad, where Michael trapped Cooper to create a machine that could operate the Dominus Librium. Kevin went to Gwen's house in search of more mana but found Max. Another fight occurred, and just as Kevin was about to kill Max, Harvey, Kevin's stepfather, stopped him. Ben appeared after Kevin and Harvey's altercation and fought Kevin, yet again. They destroyed the Rustbucket 2, at which point Gwen came out of her house. Kevin managed to disable Ben long enough so he could chase after Gwen. After a long chase, Ben returned and fought Kevin once again.
Kevin defeated Ben, but little did he know that was all part of the plan. Gwen called Cooper to tell him that Kevin would be there soon. Cooper tried to stall Kevin by using the weapons available at the military base, but Kevin dodged the missiles and approached the base. Kevin and Ben fought, with Ben no longer holding back. In anger, he almost killed Kevin, but Gwen stopped him, as they could still bring him back. They finally set Kevin to the machine, and Kevin was healed from his third mutation.
In It's Not Easy Being Gwen, it was revealed that Gwen takes her education very seriously. She was shown to come home late at all hours of the night and wakes up at 5:30 AM. She is involved in many activities, such as jogging, French, and after school karate classes.