Ben 10 characters
During a walk Ben finds the Omnitrix, which latches onto his arm. Unable to remove it, he uses its powers to become a superhero, fighting evil both extraterrestrial and criminal. However, he finds the job trickier than he imagined, especially with the evil alien warlord Vilgax pursuing him relentlessly to retrieve the Omnitrix. 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. 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!".
Ben's relationship with Gwen in the original series is complex. The two of them bicker almost constantly, can hardly agree with each other on anything (the only exception being their dislike of Max's bizarre cooking), and their fights have, on occasion, even led to physical confrontations. Despite all of this, they truly care about each other, showing genuine concern when the other is in serious danger. A prominent example is in Ben 10: Secret of the Omnitrix, when Ben is deeply saddened when it is thought that Gwen had died, and hugged her while in tears when it is revealed that she had survived.
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.
Twenty years into the future, Ben (voiced by Fred Tatasciore) 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. Ben eventually has a son named Ken, whom he teaches to used the Omnitrix in the episode "Ken 10".
In the sequel, Ben 10: Alien Force, Ben (voiced by Yuri Lowenthal)
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 thoughtful 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 picking 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. When Grandpa Max goes missing, he teams up with Gwen and
a reformed Kevin to find him. 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, and 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.
Although he, like Gwen, is a descendant from the Anodite race,
Ben does not bear the "spark" to use their powers.
Ben has learned some degree of martial arts taught by his cousin