Ben Tennyson (Classic)

Benjamin "Ben" Tennyson 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, throughout the series, learns to use the powerful alien device responsibly. This theme was further explored in the episode 'Kevin 11'.

Personality
Ben is a typical ten-year-old boy— he plays video games, rides his bike, and often gets into mischief. No matter what bizarre form Ben takes, inside he is still the same mischievous 10-year-old boy. He is something of a glory hog, sometimes taking credit that he does not deserve. He also tends to be a sore loser, especially when it is Gwen - with whom he shares a love-hate relationship - who outdoes him. Ben is not above using the Omnitrix to pull pranks, even during urgent situations. He wears a white shirt with a black vertical stripe down the middle and green pants. He also wears white and black shoes. In the episode "Perfect Day", he is shown with his pants down, revealing his blue-and-red sumo-slammer boxers.

In spite of all this, Ben is good-hearted and will stop at nothing to protect his family or anyone in danger. Even when not in alien form, Ben's resourcefulness has saved himself and others from many a dire situation, especially when the Omnitrix cannot activate or does not provide him with the form he originally wants. His most frequent catchphrase, usually said when something goes wrong, is "Aw, man!" His others include "It's hero time!" and "Going hero!".

In "Goodbye and Good Riddance", it is shown that Ben is -or was- very unpopular at school, being picked on by the other kids on a regular basis, although this changes after the entire population of Bellwood learns of his Omnitrix-fueled exploits over the summer. Also, in "Last Laugh", it is revealed that Ben had suffered from coulrophobia for some time, but gets over it in order to fight Zombozo.

Alien Force
In the sequel, Ben is a much more mature and resourceful character, having learned the value of teamwork through his role as a goalkeeper for his soccer team, at the same time growing out of his childish antics, and is far more adept when using the Omnitrix, actually thinking about which alien would be most effective against an opponent or the most appropriate for a situation, rather than simply selecting the one with the most physical power as he originally did, though there is still a bit of the young Ben Tennyson in him. His relationship with Gwen is also better; they no longer fight, and their quips about one another are more friendly.

He now sports a black 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 also has a girlfriend named Julie Yamamoto, who helps his team from time to time. 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 recalibrated, giving 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 too is Ben hurt as a result, though this has not proven to be any real problem so far. Contrary to the Omnitrix's previous ill-timed deactivations, the new recalibrated 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 Anodite race, Ben does not bear the "spark" to use their powers. Ben has also learned some degree of martial arts taught by his cousin Gwen.

Evolutions
Ben is now 16 with new aliens and a new Omnitrix.

Possible Future
Twenty years into the future, Ben has become a full-time superhero. He no longer bothers to conceal his identity, as he is recognized everywhere as Ben 10,000 or Ben 10-K, no matter what alien form he is using. He also has 10,000 alien forms, hence the name, and has once again unlocked the Omnitrix's master control function, allowing him to switch forms at will. Having been fighting crime for such a long time, Ben 10,000 has grown into a more strict and serious character, going so far as to stop naming his aliens (which the present Ben considers "half the fun" of using them), and has a darker way of dealing with villains, such as defeating Vilgax by literally dismembering him, though his interaction with his past self in the episode "Ben 10,000" causes him to lighten up somewhat, naming his aliens all over again. Ben's alien forms have aged with him, which is evident in their appearances and abilities. For example, Ben 10,000's XLR8 is noticeably taller with grey outlines in place of the ordinary blue, as well as being considerably faster. In an alternate timeline, Ben eventually has a son named Ken (named after Gwen's brother), whom he teaches to use the Omnitrix in the episode "Ken 10". This future however is less possible prior to Alien Force neglecting most possible future occurrences. This episode might be non-canon because he might marry Julie Yamamoto rather than Kai Green.

Behind the Scenes

 * In the original series, Ben is voiced by Tara Strong.
 * In Ben 10: Alien Force, Ben is voiced by Yuri Lowenthal.
 * For the episodes "Ben 10,000" and "Ken 10", Ben is voiced by Fred Tataiscore.

Triva

 * He is part Anodite, he just can't use Anodite powers. However, considering Azmuth added the DNA of every sentient race in the galaxy to the Omnitrix, it is likely he may have an Anodite form accessible through the Omnitrix.
 * Apparently, he can't give good advice, implied in 'Save the Last Dance'.
 * He has a strong like for smoothies, and chili fries.
 * http://watchben10now.blogspot.com