Fandom: Ben 10/Ben 10:Alien Force/Ben 10: Ultimate Alien

Erexians are a species of peaceful shapeshifters. Given time and practice, they can take the form of any alien species in the universe.

Decades before he created the first prototype of the Omnitrix, Azmeth crash landed on the planet of Erexis. The Erexians took him in and nursed him back to health. As he observed their way of life, he grew increasingly intrigued by their empathy for and understanding of the other alien species. Their peaceful nature sparked his inspiration for the Omnitrix - a device that would allow him to transform, to understand the other species as the Erexians did.

He convinced their leader to give him a sample of Erexian DNA so he could build such a device. After some convincing, they agreed and he returned to Galvin to begin work on the Omnitrix.

Others began to view the Erexians as a threat and Azmeth provided them with planetary defenses to help ward off the newly arising threats.

When Zena was 8, Vilgax attacked. Having studied the failures of previous attackers, he managed to overpower the defenses and make it to the planet's surface.

Although the Erexians were not fighters, their ability allowed them to hold their own against his attacks. It took Vilgax a month to capture Sector 1 of Erexis. When the tribe fell, the surrounding sectors warned the rest of the planet and they began a mass exodus. Many of the able-bodied citizens chose to meet Vilgax on the battlefield and buy the others time to escape. Among those volunteers, Zena's father - Ovarin - joined the fight.

Having learned how to fight the Erexians, Vilgax quickly battles his way to Sector 5, just outside of Zena's tribe. With no more time, they flee the planet with who and what they have.

The Erexian survivors travel space looking for a new planet for them to call home. They send out scouts to survey the planets.

Zena, at age 10, is sent to earth. She spends a year learning and observing the planet and the humans. Just before she was going to return to the fleet and report, her ship gets destroyed in the crossfire of a fight between two aliens.

She shocked to find that one of the aliens turns into a human after the battle. Intrigued and unable to leave the planet, she follows this strange creature, half-convinced that it's another Erexian.

As she watches him and his companions, she discovers that the boy has the Omnitrix - the device Azmeth modeled after their DNA.

During the following battles, she gets bolder and throws herself in harms way to help protect the civilians during the boy, Ben's, fights.

Ben's grandpa starts to take notice of her involvement.

When they finally track her down and corner her, she explains her situation and why she's following them. They try to help her find a way off the planet while also fighting the aliens coming after Ben and the Omnitrix.

When Vilgax himself comes after the Omnitrix, he tells Zena that he destroyed the Erexian fleet, killing the rest of her species. After he's defeated, she goes looking for the fleet, not wanting to believe that she was the last of her kind.

She finally returns to help Ben, Gwen, and Max as they deal with a rogue Ghost Freak.

When Ben figured out the master control for the Omnitrix, Vilgax returns. They fight him off.

Upon Max's invitation, she stays with them on the Rust Bucket, helping them fight off aliens.

They notice a pattern in some of the aliens they face and discover that Ghost Freak is still alive and after Ben.

After defeating Ghost Freak in space, An old ally returns. Ben accidentally activates the Omnitrix's self-destruct and they race to find it's creator.

Vilgax follows them and finds Azmeth. Ben, Gwen, and Zena protect him and manage to stop Vilgax. Azmeth stops the self-destruct and they return to earth.

Zena joins the Plumbers, riding around with Max for the next five years learning and training.

When Max disappears, he leaves her a message, telling her to find Ben and Gwen. They reunite, but with someone new - Kevin Leven. She's hesitant to trust Ben's childhood nemesis, but the Osmosian proves himself during a fight with the DNAliens.

Ben's parents let her stay with them, initially unaware of her true identity. She helps them fight off the Highbreed.

She tries to hide her identity from everyone, explaining that she and Max had run into trouble from bounty hunters and assassins looking for "The Last Erexian."

When Vilgax returns, she fully embraces her identity to help Ben as he recaptures his escaped aliens.

She tries to help Kevin by letting him absorb her powers, but it doesn't work.

Vilgax captures her with the help of Albito, who stole Azmeth's Ultimatrix. He tries to use her against Ben.

In an attempt to get the Omnitrix back, Ben sets it to self destruct. Thinking he's bluffing, he doesn't remove him. As it reaches the final countdown, he grabs Zena and presses the Omnitrix against her chest as it explodes.

Gwen manages to pull her out as she escapes with Kevin and they watch Vilgax's ship explode.

Ben's identity is revealed to the world. As he basks in the fame, Zena hopes that no one has made the connection to her true identity.

When they start coming across some strange aliens, sharing tales of a dangerous Osmosian named Aggregor, they jump in to help the aliens return to their home worlds.

Unbeknownst to them, Aggregor cuts off the aliens and recaptures them.

When he comes for the last alien at Kevin's garage, Ben and the others defend him. During the battle, Zena transforms to protect Ben and gets hit with a blast that leaves her unconscious and she reverts to her human form, revealing her true nature.

In the chaos of the fight, Aggregor kidnaps Zena along with the other alien.

The others manage to track them down and destroy Aggregor s machine, but not before he's absorbed all six aliens, including Zena.

Her ability to shapeshift - to adapt - allows her to hold onto some form of self, even within Aggregor. She uses this small advantage to keep Aggregor from using her powers.

At the Forge of Creation, when Kevin absorbs Aggregor's powers, Zena uses what little will she has to use Kevin to pull herself out of Aggregor and escape the Osmosians.

Unfortunately, most of her power still flows into Kevin. She only manages to hold onto her human form. Kevin doesn't realize he has her power, which gives them a chance to stop him as he goes on a power-crazed rampage against those who had wronged him in the past.

With help from an old friend, they build a machine to absorb all of Kevin's excess energy and return it to it's rightful owners. Zena gets her powers back.

With an uptick in activity among the ruins of her home world, Zena isolates herself from the others and ups her surveillance of Erexis.

Ben's mom makes her get out of the house for a girl's day. As they leave the mall, an armored bounty hunter attacks.

In the midst of the fight, the stranger removes his helmet, revealing that he's an Erexian. Shocked, Zena brings him back to Ben's house to explain everything.

The Erexian - Zarith - tells her that he was off world when Vilgax attacked Erexis. He returned to find the planet ravaged, his home destroyed, and his family killed. At a loss of what to do next, he lid low and became a bounty hunter, one of the few occupations that allowed him to search the universe and hide his true identity without raising suspicion.

As Zena tried to connect with Zarith and show him Earth, he finally cracks and attacks her, revealing that he blames her dad for his family's death as her father and his mother had been friends and Zarith believed that her father had abandoned them.

With the fleet destroyed, he's unable to take his revenge on her dad, and so he decides to take it out on her.

The others help her fight Zarith off and he disappears.

Zena follows him off world and tracks him down on a distant planet. He catches her by surprise and manages to capture her. He chooses to turn her over to the Insurgence, who quickly double cross him and lock him up right alongside her.

She uses their imprisonment to explain what really happened during Vilgax's invasion. Her father had gone to the frontlines with a band of volunteers as soon as they got word in Sector 6 of Vilgax's attack. Everyone retreated to the farthest sectors and boarded the ships to evacuate the planet. The ships on sector 6 barely escape before Vilgax reached them and unfortunately there were many casualties in sector 5.

Once she convinces Zarith she's telling the truth, he apologizes for attacking her and they work together to come up with an escape plan.

In the chaos of their escape, Zena makes it to an escape pod, but Zarith is caught fighting off their captors. He launches the pod before Zena can get out to help him.

Zena watches as the ship finally explodes from damage they'd caused during their escape. With that, she truly is the last Erexian.

She returns to earth to find Ben and the others in the midst of a war with an inter dimensional demon known as the Dagon.

She helps them fight off the Esoterica and defeat Vilgax and the Dagon.