Ben Tennyson (Classic)

Benjamin Kirby Tennyson, more commonly known as Ben or Ben 10, is the main character of the series.

He is first introduced in the episode And Then There Were 10, where he finds the Omnitrix and then, throughout the series, learns to use the powerful alien device, including the responsibly of wielding it, to become a true hero.

It should be noted that Ben is three-quarters human/one-quater Anodite. If seen briefly, after Ben reverted back from Spidermonkey ,,,,,,,,,, Ben's eyes gleam pink for a moment. This means that Ben has Anodite powers within him but it is unknown what keeps Ben away from getting the spark like Gwen.

Appearance
Ben has brown hair and green eyes (in Alien Force his eyes appear to be of a darker green). In the original series he wears a black and white t-shirt and green pants. In Alien Force he wears a black t-shirt with a green jacket over it and a pair of jeans. His jacket in Alien Force has the number 10 on it.

In the original series it is also mentioned several times that Ben has poor hygiene.

Original series
Ben was originally a typical ten year old boy, who grew up in Bellwood, and was unpopular and bullied in his school.

However, his live changed the day he went in summers holidays with his grandfather Max and his cousin Gwen. A short time after they left Bellwood, Ben went on a walk and witnessed the crash of a strange capsule from space. This capsule happened to contain the Omnitrix, a powerful watch-like device, who fixed itself on Ben's wrist.

At first scared, Ben soon discovered that using the Omnitrix, he was now able to transform in ten super-powered alien creatures. Unable to remove it, he eventually learned to used it (though with relative problems) in order to become a super-hero. Though he occasionnally arrest ordinary criminals, he was quickly led to also fight super-villains, starting with Dr. Animo, Kevin 11, and ultimately Vilgax, a vicious alien warlord who wanted to get the Omnitrix for himself.

Despite being very immature and occasionnally using the Omnitrix for minor selfish purposes, Ben proved to be a valuable wearer for the Omnitrix, defeating Vilgax several times (though it was mostly due to the help from Gwen and Max) and saving several times peoples.

During this series, Ben's favorite alien is Fourarms, showing his tendency to favor brute force over well-thought plans.

Alien Force
Although he, like Gwen, is a descendant from the Anodyte race, Ben does not bear the "spark" to use their powers. Unusually enough, in the episode Voided, Ben seems to be able to see Animo absorbing energy. This may or may not be related to his Anodyte heritage. But Ben has been able to wield the Omnitrix better than any other human could have. This may/may not be because of his Anodite heritage. Ben has also learned some degree of martial arts taught by his cousin Gwen.

Ben also has a girlfriend named Julie Yamamoto, who marks her first appearance in the pilot episode Ben 10 Returns: Part 1 as a crowd attendent to Ben's soccer game. She then next appears in Pier Pressure, where Ben asks her out and she discovers the Omnitrix and finds it cool instead of running away like Ben thought. It seems that Ben has a very concerned and protective feeling for her and the same with Julie. Ben seems to trust Julie the most. For instance, when Ben's hand is cut-off, it goes in search of Julie and not Gwen or Kevin. And when Big Chill takes over Ben's personality, it is Julie who sincerely takes his problem seriously and tried to help him in every manner. Ben even travelled half-way across the galaxy only to fight against the claim of Baz-El for Ship only for Julie.

When Grandpa Max goes missing, he teams up with Gwen and a reformed Kevin. In the first two seasons, it is shown that Ben has matured dramatically and is a very capable good leader. But in Season 3, after their success at saving the universe at the hands of the Highbreed, Ben seems to have gone back to his old self. He has this basic dialogue of saying that "And that's because I saved the whole entire universe" of which Gwen and Kevin are fed up of. Oftenly they only complete his this dialouge. Ben had also tampered with the Omnitrix which led to the release of Goop, Chromastone, Spidermonkey and Way Big which he got back whereas mutuating Kevin for the second time. Ben and Gwen have also revived thir famous love-hate relationship with each other. Now Ben considers that his overconfidence is his most appealing quality and thinks that he is adorable.In The Final Battle: Part 2, Ben self-destructs the Omnitrix and gains the new Ultimatrix.

Ultimate Alien
In sequel Ben 10: Ultimate Alien, It takes place just after the Alien Force finale, sixteen-year-old Ben's identity is somehow revealed to the world and he's now a megastar super hero loved all over by kids but distrusted by many adults. This series will also feature Ben's new car, the DX Mark 10, which marked it's first appearance in Ben 10: Alien Swarm, the car being gifted reluctantly by Kevin. Also he will be seen with Julie, now sharing a stronger bond with her and Julie again helping their team from time to time. He and Julie will also share their first on-screen kiss (though Julie kissed him on his cheeks) in Fame. He also got a lot of confidence after Julie kissed him and Ben appeared to be utterly shocked at Julie kissing him. Also, Ben and Kevin are now true friends and not rivals. Ben will not be armed by the Omnitrix but by an evolved version of the Omnitrix, the Ultimatrix which evolves his aliens, and also has every alien he as ever turned into.

Personality
For most of the series, Ben is portrayed as an immature, sometimes cocky boy who would occasionally take credit he doesn't necessary deserve. He tempers his immaturity in Alien Force due to Max's disappearance and the threat of the High-Breed Invasion, but tends to relax and turn a little back to his original self in the third season. He also had a complex love-hate relationship with his cousin Gwen in the original show.

Despite his immaturity, Ben is good-hearted, and his actions are motivated above all by a strong and sincere will to help other people. He will stop at nothing to protect his family or anyone in danger. Sometimes, his idealistic nature tends to make him act naive.

Though often said by many other characters to be quite unintelligent, Ben actually proves to be resourceful and cunning when needed, which saved him from many situations, especially when the Omnitrix cannot activate or doesn't provide him with the form he originally wanted. When he toned down his immaturity in the two first seasons of Alien Force, he proved to be a capable leader for his team. Although, after his success at saving the universe from the High-breed invasion, his overconfidence caused him to revert to his immature personality.

It is also pertenant to note that while he has not inherited his Grandmother Verdona's "spark", Ben has inherited her 'spirit', evident by the sense of humor they both share.

Kai Green
Kai Green is a girl of Navajo descent and the granddaughter of Wes Green, a former Plumber and a long time friend of Max Tennyson. She appears in the episode Benwolf where Ben catches a glimpse of her dancing and is immediately smitten. At the end of the episode, Ben attempts to establish a relationship with her but is immediately rebuffed when he learns that she had just admired him in his alien form.

Julie Yamamoto
Julie Yamamoto is an Asian-American student and teenage tennis player who is the current Ben's love interest. She first appears in the pilot episode of "Ben 10: Alien Force" as a crowd attendant to Ben's soccer match. At the end of the two-part season two finale "War of the Worlds", Ben and Julie get close to kissing, but decide against it as Gwen, Kevin, and Max were all looking on. In the series premiere of "Ben 10: Ultimate Alien" "Fame", Ben and Julie share their first kiss; although technically, Julie kissed him on the cheek, who appears utterly shocked. It said that Ben and Julie will be kissing often throughout the series as their affection for each other grows.

Elena Validus
Elena Validus is one of the Plumbers' kids and a former member of Ben's soccer team. She is mentioned by Gwen as Ben's first crush (though this contradicts what was seen in the original series as Ben met Elena when he was thirteen while he met Kai when he was ten). Ben had to convince his soccer team mates to let her join. She appeared in the live-action film, Ben 10: Alien Swarm. It is said that she might appear in Ben 10: Ultimate Alien .

Powers and abilites
Ben is the wearer of the Omnitrix and later the Ultimatrix, which give him the incredible power and ability to modify his own genetic code in order to turn into various Alien creatures. He traditionnally has an arsenal of 10 aliens at the beginning of the original serie and Alien Force, but he later gains additionnal forms both by unlocking other aliens or scan DNA on the creatures he meets. At the end of the original series, his arsenal included 20 aliens, while his current complete list is 38 aliens discovers (Ben 10, Ben 10: Alien Force, and Ben 10: Ultimate Alien), but he have yet to Access the future Aliens,but he can now become ultimate forms versions of his old Alien Force forms.

When transforming into an alien, Ben gets all the creature's features, including its voice, abilities, weakness and appearance. Though he mostly retains his personnality, there are some cases where the transformation causes change in it, such as Rath becoming far more aggressive, Spidermonkey acting more childish, or Big Chill being affected by his species' reproduction instincts. Two of the aliens, Ghostfreak and Eon, even managed to take over Ben's personnality twice, though this was a special case.

In addition to his Omnitrix shape-shifting powers, Ben, in Alien Force, has been trained in hand-to-hand fight by his black belt cousin Gwen (as shown in Be-Knighted), his former plumber grandfather Max, as well as various years-fighting aliens, and received a basic Plumber training (all of this according to Dwayne McDuffie). He is much more altheltic than his younger self. Though he has only been trained on week basis in order to be able to handle himself if the Omnitrix doesn't work, he's still proved to be quite skilled, being able to take off Manny's blasters while in human form in Above and Beyond.

Trivia

 * Ben suffered from a fear/dislike of clowns up until the events of Last Laugh, when he realised that there were actually more serious things to be scared of, like "losing [his] family to some 'goofball emotional vampire'," finally 'scaring the fear' right out of him.
 * In A Change of Face, it is mentioned that a 10-year-old Ben still slept with his teddy bear, called "Furry Fred(dy?)." 
 * Although he has Anodite lineage, he has not shown signs of having Anodite powers. Altough If seen briefly, after Ben reverted back from Spidermonkey, in Fame Ben's eyes gleam pink for a moment. This means that Ben has Anodite powers within him but it is unknown what keeps Ben away from getting the spark like Gwen.
 * As mentioned in Primus, he is just a "regular guy" without the Omnitrix. This means that despite being a Plumber's grandson, Ben does not have any superpowers. This makes Ben one of the two official Plumber kids who does not have natural powers.The other is Elena.
 * Ben's situation is like Julie's, it's the Omnitrix adding to Ben's strength. Julie too, though not related to the Plumbers, only has superhuman abilities and durabilities if her pet Ship, a Galvanic Mechamorph, can merge with her. This point is noted in the episode Vreedle, Vreedle when Ship enveloped her, becoming a exoskeletal mecha suit.
 * As revealed in Good Copy, Bad Copy, Ben's left eye twitches whenever he tells a lie. Kevin seems to be the only one who noticed this.
 * He has a strong affinity for smoothies and chili fries.
 * In season 3 Ben has not changed his clothes like Kevin and Gwen did.
 * Like Max and Gwen, Ben thinks that the summer he found the Omnitrix was the best summer ever.
 * He made a cameo appearance alongside several over cartoon characters in the BBC Children in Need's 2009 Charity Single as a member of the "Peter Kay's Animated All-Star band".
 * In Ben 10 Alien Force, Ben usually wears his "lucky T-shirt" during soccer.
 * Ben's aliens do not have the same costume style as in Ben 10, Ben as when he wears a swimming costume, pajamas or a suit he still wears his black and white t-shirt in alien form.
 * In Ben 10: Alien Force, Ben almost always calls out the name of the alien he turned into right after the transformation is complete.