Ben Tennyson (Classic)

Benjamin 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.

Appearance
Ben has got short 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 got the number 10 on it.

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

Original series
In the original series, Ben likes to play hero, sometimes even taking credit that he does not deserve, and appears to be a sore loser, especially when it comes to his cousin Gwen. On more than one occasion, Ben uses the Omnitrix for minor reasons or for his personal gain (as shown in Washington B.C. and Kevin 11).

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

Alien Force
He now wears a black sports shirt, a green jacket with a white vertical line and the number 10, while his soccer uniform resembles his original clothing. He found a way to remove the Omnitrix roughly five years before the series began, allowing him to live a normal life. Ben now frequently patrons a local fast drinks place called Mr. Smoothie and indulges in strange flavors, (such as chocolate and carrot,) as well as a fast food place called Burger Shack.

Ben also has a girlfriend named Julie Yamamoto, who helps his team from time to time. He has also developed a romantic relationship with her in the due course of time. In the War of the World's 2-parter, Ben and Julie were about to kiss when they decide against it as Gwen, Kevin and Max were looking on and promises her to walk her to school the next day. Ben is also very concerned and protective about Julie. He seems to trust Julie the most. He always seeks her help first before anyone else. It is seen in "Single-handed", when Ben's cut-off hand hand goes to find Julie instead of Gwen or Kevin.Even in "Save the Last Dance" when nobody pays attention to Ben's problem, Julie is the only only one who tried to help Ben in any manner. They also seem to share a great bond with each other and Ben is very possessive about her and really loves her. He also seems a little worried when hhe comes to know know that Julie will help him save the world in "War of the Worlds" as she does not have any power.

When Max goes missing, he teams up with Gwen and a reformed Kevin to find out about an alien conspiracy Max was working on. The Omnitrix has been re-calibrated, giving Ben access to a new set of alien forms; in addition, it reconfigures into a more watch-like shape. It also carries a new weakness: if Ben's aliens are hurt, when the Omnitrix times out, so Ben is hurt too as a result, though this has not proven to be any real problem so far.

Contrary to the Omnitrix's previous ill-timed deactivation, the new re-calibrated Omnitrix appears to deactivate more or less to Ben's will or simply manually by rotating the dial as shown in the episode Alone Together, additionally it can be used multiple times in succession or indefinitely when used at its maximum, though its power will eventually deplete and will require time to recharge as shown in the episode Good Copy Bad Copy. 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. Ben has also learned some degree of martial arts taught by his cousin Gwen.

In season three, it is shown that Ben has resumed acting superior and making rash decisions, thus leading the Omnitrix to decide which alien would be best for the situation. Gwen and Kevin have both been tired of this superior attitude ever since Ben, Gwen, and Kevin stopped the Highbreed invasion. Ben also has a usual dialogue heard in most of the episodes of season 3 which Gwen and Kevin hate the most and that is when Ben says that, "And that's because I saved the whole entire universe."

Half of the time in season 3 Gwen and Kevin only complete his this dialogue. Ben has also begun to tamper with the Omnitrix, which led to the release of archetypes Goop, Spidermonkey, Chromastone, and Way Big, which he got back. He is now fighting against enemies old and new, using familiar aliens from the original series such as Diamondhead, Upchuck, Cannonbolt, Way Big, and Ghostfreak, all the while gaining new aliens like Loadestar, Nanomech, and Rath. In the finale of the show, Ben gets the new device called the Ultimatrix after the Omnitrix was self-destructed.

Possible future
See: Ben 10,000 (character).

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 War of the Worlds, Ben and Julie get close to kissing, but decide against it as Gwen, Kevin, and Max were all looking on.

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.

Trivia

 * Ben also suffered from a fear of clowns until the episode, Last Laugh.
 * Although he has Anodite lineage, he has not shown signs of having Anodite powers.
 * 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 animated All-Star band".
 * In Ben 10 Alien Force, Ben usually wears his "lucky T-shirt" during soccer.

Ben Tennyson Ben Tennyson