Sir George: Tell me, young Master Tennyson. How can you, who has yet to live a single lifetime, know better than I, who has lived a thousand?...You've had people second guessing you, Master Tennyson. Everyone from Azmuth, to your parents, to those jackals in the media. Does it not frustrate you? Their thinking that they know better than you? Welcome to my world.
Ben Tennyson: No matter what you think, sooner or later, that sword will corrupt you!
Sir George: It didn't before. I achieved great things with it. My feats are legendary. Mine have stood the test of time. Mine have inspired millions. What will your legacy be? With what stars will you align? How many times have you known in your heart that your way is best? How many times have your plans been thwarted because the very people you're trying to help won't trust you?
Ben: What do you want?
Sir George: To be left alone, so that I may destroy my ancient enemy!
It started when an alien device stuck itself upon his wrist, now Ben Tennyson fights off evil from earth or space. Here are the smartest and most charming he and his allies have ever faced.
Order by series release date.
All spoilers are unmarked. You Have Been Warned!
Multiple Series
- Hex is a sorcerer from Ledgerdomain, becoming a refugee on Earth with his niece Charmcaster, where he prioritizes increasing his magical power. Coming into conflict with Ben and Gwen after they steal one of the Charms of Bezel, he lures them into a trap and reacquires it, only for the charms to be destroyed. Aided by Charmcaster, Hex uses a ritual to recreate the charms and is momentarily successful despite betrayal from his niece. Hex attempts to restore his youth, tricking Team Tennyson to lead him to the Fountain of Youth and stalls them to get ahead. Years later, Gwen's ill-fated time travel experiment creates a Bad Future where Hex succeeds in conquering the world, fully aware Gwen is the cause and tries to prevent her from correcting reality. Later, Hex starts reforming, freeing Gwen from an impenetrable force-field he trapped her in after finding out she intends to help his niece. Eventually Hex pulls a Heel–Face Turn and abandons his villainous ways, becoming a beloved professor at Friedkin University, who desires to live a peaceful life with Charmcaster, but remaining a powerful sorcerer.
- Dr. Viktor is one of Zs'Skayr's minions and the most intelligent among them, who generally remains fiercely loyal to his master. Following his master's first demise, Viktor successfully infiltrates NASA by posing as a human in order to hijack a space shuttle. Simultaneously fighting off Ben, Viktor manages to finish constructing a machine that brings Zs'Skayr Back from the Dead. Viktor had also organized all the components needed for Zs'Skayr's plan to darken the world with Corrodium. Years later, after Viktor has his body stolen by King Xarion, Zs'Skayr frees Viktor, who pledges his loyalty to his master out of gratitude. However, Viktor does not support Zs'Skayr's new plan to resurrect the Vladats as an army, given how they fed on and enslaved Viktor's own species. In the end, Viktor defects and helps Ben in defeating both Zs'Skayr and the only Vladat, Lord Transyl.
- Inspector 13 is a Techadon Weapon Master who came to Earth to investigate the high frequency of defeated Techadon robots. Kidnapping Ben, Inspector 13 intends to remove and reverse-engineer the Ultrimatrix to harness its technology. However when warned by Ben of the self-destruct feature, Inspector 13 instead succeeds in hacking the Ultimatrix. When interrupted by Gwen and Kevin's rescue attempt, Inspector 13 is able to hold them off with an assortment of weaponry designed to counter different enemies. After becoming an independent businessman operating on Earth, Inspector 13 is able to lose his pursuers in a high-speed car chase, then prepares an ambush having anticipating being found. Inspector 13 also reveals he saw through Albedo's disguise, then fights evenly against his stronger opponent, using cunning application of his tech. When running his business without interference, Inspector 13 is a very efficient Snake Oil Salesman, able to con clients into buying difficult to use weaponry.
- "Ken 10": Kevin 11,000 is the alternate future's villainous version of Kevin Levin. A cold, ruthless criminal who was locked inside the Null Void for decades, Kevin 11,000 took advantage of his imprisonment to drain the powers of every single prisoner his Arch-Enemy Ben locked in with him. Manipulating his young son Devin into befriending Ken Tennyson to gain access to the Null Void generator, Kevin 11,000 orchestrates his escape from confinement, then takes Ken as a hostage to lure his father Ben to a fight. Kevin 11,000 thrashes Ben and Ken both with his power and cunning, tanking even their most powerful attacks and proving unstoppable until Devin betrays him.
- Reinrassig III is a commander of the Highbreed alien army, one who grows beyond his kind's xenophobia to become a true leader. Forced to ally with Ben 10 when they are stranded on an alien world, Reinrassig cleverly outwits and takes down a variety of the planet's natural predators, while growing more friendly and understanding of Ben. Inspired by Ben's heroism and sharing his DNA to heal Reinrassig, the Highbreed commander later personally sways the entire Highbreed supreme council into ending their genocidal plans and accepting other races, getting himself elected as the new ruler of their kind. Reinrassig becomes a genuine friend and ally to Ben, assisting him in saving the galaxy and homeworld while paving the way for a tolerant, accepting Highbreed society.
- Verdona is Ben and Gwen's grandmother, a feisty Anodite who believes in freedom from physical constraints. First arriving on Earth as a prisoner, Verdona helped Max Tennyson take down her captors even when she was powerless, falling in love with the man in the process. Returning to Earth years later, Verdona charms her grandkids and tries to first convince Gwen to embrace her Anodite side, then attempts to force her into the role by fighting her and her friends. Ultimately accepting Gwen's choice to stay on Earth, Verdona wishes her grandkids the best and later assists them in taking down rogue Anodites.
- Sir George is the immortal founder of the Forever Knights, who repelled Dagon centuries ago using the sword, Ascalon, cutting out the monster's heart and sealing it in another dimension. Having sensed the breaking of Dagon's seal, Sir George returns from retirement to unify the splintered Forever Knights and then tasks them with the exile of all aliens residing on Earth. When the alien purge fails, George is undeterred and focuses his efforts on stopping Dagon, retrieving Ascalon to restore his youth and power. When asked to surrender his sword by Azmuth and challenged by Ben, George demolishes Ben's team with ease yet still honorably spares their lives. Upon gaining respect for Ben, George allies with them to fight off Dagon's forces. Mistakenly believing Ben had been killed, George attempts to avenge his ally. George ends up being killed trying to vanquish Dagon and is remembered fondly by Ben as having died a hero.
- Khyber is the alleged "greatest huntsman in the galaxy". Hired by Dr. Psychobos and Malware to hunt down all of the predatory species for the Nemetrix and later the Omnitrix itself, Khyber thoroughly studies his prey and begins hunting Ben Tennyson, using the Nemetrix attached to his pet which he controls by whistling, eventually succeeding in subduing and capturing Ben. Assisting in the attack on Galvan-Prime, after being disrespected by Psychobos, Khyber turns on him and escapes with the Nemetrix. Later teaming up with Albedo, breaking him out of prison and swapping the real Ben in his place, Khyber then hunts Ben in his own personal reserve using his new pet. Fighting the heroes over possession of Azmuth's brain, Khyber gets captured and resists interrogation until the information is forcefully extracted from his mind. Escaping yet again, Khyber teams up with Skurd, offering the Nemetrix in exchange for his powers.
- Attea is the princess of the Incurseon empire and daughter of Emperor Milleous. After being thwarted in her first attempt to usurp her father, she is made a general of his army and invades several planets including an assassination attempt on Vilgax. Acquiring mind control serum made from harvested Amber ogia, she uses it to create an army of Way Bads. Attea and Milleous launch a full-scale invasion on Earth, succeeding in taking it over and exiling Ben Tennyson. However Ben manages to escape and returns as Bullfrag and helps to defeat the Incurseon and Way Bad armies. Upon Milleous being arrested, Attea reveals she was the one who freed Ben and that the entire war was one elaborate ploy to get her father removed so she could take over the empire.
- Vilgax was once the assistant of Azmuth, but stole the Omnitrix to become a warlord, leading Azmuth to drain half of Vilgax's DNA into the Omnitrix, who manifests to Ben as "Gax". Posing as "Vil" and becoming Ben's Evil Mentor, Vilgax manages to reabsorb his power, and later fixes Ben's malfunctioning Omnitrix to remove Ben's advantage, before attempting to extract it. Surviving his ship sinking into lava, Vilgax returns many times to menace Team Tennyson, manipulating several villains including: Dr. Animo, the Weatherheads, and Zombozo into alliances with him intending to betray them. Vilgax nearly tricks Ben into believing the Omnitrix is dangerous and surrendering it to Vilgax. Though Vilgax is right about the danger Shock Rock poses to the Earth, causing the Fulmini Invasion where Vilgax teams up with Ben to protect the Earth. Vilgax also manipulated Kevin into creating the Antitrix by transmitting blueprints in his dream, before Vilgax takes the Antitrix for himself and becomes AntiVilgax, then steals the Omnitrix Key to unlock Celestialsapien DNA and becomes Alien V. Far more manipulative than Classic Vilgax, while being far less nastier, this Vilgax becomes far more likable and compelling to watch.
