Benjamin "Ben" Kirby Tennyson was an average ten-year-old kid, until he found the Omnitrix, a powerful watch-like device that allowed him to turn into ten different alien species. Though initially immature and clumsy, he grew as a true hero. By the time he was sixteen, he had become famous in not only his hometown of Bellwood, but on Earth and beyond. Ben has also become a member of the Plumbers.
In Ben 10: X Evolution, Ben wears a long-sleeved black T-shirt inside a green hoodie with two black stripes and the number 10 on it. The sleeves of the T-shirt are exposed at his hands since the sleeve of the hoodie is folded. He wears brown pants and green and white shoes. He wears the Evolutrix on his left wrist. His has a spiky hair.
Ben is initially portrayed as a cocky, arrogant and immature boy who tends to make jokes even when fighting. He easily gets full of himself and enjoys attention. This attitude can sometimes make him look obnoxious or dumb, often resulting in criticisms from Gwen and later Kevin. It also causes several conflicts between him and Azmuth.
Despite his immaturity, Ben is actually good-hearted, and his actions are motivated above all by a strong and sincere will to help and save others in need. He's shown to deeply care for other's lives, and would choose to save people by himself even when he dislikes them (such as Cash and JT). When meeting an enemy in trouble (like Kevin or the Highbreed), he'll usually attempt to help them rather than win the hard way. While this somehow overly idealistic nature is often criticised by Azmuth, most characters usually consider it as Ben's most important quality. Paradox once even stated he had the gift to make the right choices at the right moments.
In X Evolution Ben always tries to act smart even when in trouble rather than fighting the bad guy. Sometimes he even gets the situation worse.
Powers and Abilities
Ben is the wielder of the Omnitrix (prototype) (later the Ultimatrix and the Omnitrix of Omniverse and now the Evolutrix), which gave him the power to modify his own genetic code in order to turn into various alien creatures, literally making him an alien shape-shifter. Traditionally, he could only transform into 10 aliens at the beginning of both the original series and Alien Force, but he later gains additional forms by either unlocking them or by scanning the DNA of aliens he meets. At the end of the original series, his arsenal included twenty aliens, while his current complete list is sixty-three aliens discovered (Ben 10, Ben 10: Alien Force, and Ben 10: Ultimate Alien, 72 if Ultimate forms are included).
When transforming into an alien, Ben gets all the creature's features, including its appearance, voice, all of its unique and special abilities and powers, strengths and weaknesses. Though he mostly retains his personality, 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 reproduction instincts. Two of the aliens, Ghostfreak and Big Chill, even managed to actually take over Ben's personality twice.an.
In addition to his Omnitrix/Ultimatrix powers and abilities, fifteen-year-old Ben, in Ben 10: Alien Force, has been trained in hand-to-hand combat by his black belt first 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. Though he has only been trained on a weekly basis in order to minimise his reliance on the Omnitrix/Ultimatrix, he is still proved to be quite exceptionally skilled in basic hand-to-hand combat as well armed and unarmed combat, being able to easily dodge shots from Manny's blasters and proceed to disarm him while in human form in the episode Above and Beyond. Ben was able to hold his own against Pierce and Max hinted that Ben was a highly skilled fighter even as a human in Voided, expressing surprise about the fact he lost to Pierce (though it is then revealed that Ben had lost on purpose). Another hint of his exceptional hand-to-hand skill is when he succeeded in the Plumbers' Academy with a 95 out of a 100 (without using his powers). He is also shown to be a crafty fighter. However, according to Matt Wayne, Ben isn't a trained fighter and that he uses freestyle fighting. Ben is also a cross dominant, skillfully wielding tools and weapons in either hand, in human or alien form, also when he was fighting Pierce, Pierce smacks Ben's left hand and Ben says that was his video game hand.
In Where the Magic Happens it is shown that Ben has a good memory, as he was perfectly capable of remembering and writing down the mystic rune-like symbols for entering the inter-dimensional realm of Ledgerdomain with just one glance and seeing them from a distance. He was able to write the runes down with perfect accuracy.
In X Evolution it is shown that Ben has been trained in Kung-fu.