Ben's physical appearance has evolved throughout the series from a ten-year-old to a fifteen and sixteen-year-old teenager. However, he retains some recurring characteristics. He has short brown hair, green eyes, pale skin, and he's quite skinny for his age (though his various future selves are portrayed as quite muscular), though he shows a lot of muscle definition due to being athletic. In the original series, his usual clothes consisted of a black-striped, white shirt with short sleeves, green pants and black and white shoes with black stripes. Starting with Alien Force, he wears a black shirt, blue pants and a green jacket with the number 10 on it, and black shoes, clothes he retains in Ben 10: Ultimate Alien. Ben wears the Omnitrix and Ultimatrix on his left wrist in a watch-like manner. Like all the other main characters, his physical appearance hasn't changed much.
In the new series Ben 10 Omniworlds, Ben looks the same.
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 him several conflicts with Azmuth. These traits, however, as hinted in The Forge of Creation, stem from Ben's attempts to hide his own fear about the situation (though he denied it and said he was actually oblivious). Even so, he's matured since the first series and although he can be goofy, he's also capable of great leadership skills and tends to get serious when the situation requires it.
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). This causes him to have a strong dislike for sacrifices or life compromises and occasionally act against reason, such as choosing to save half-cured DNAlien Tyler over seizing the key for the Highbreed's invasion (Inside Man) or trying to save the Sentinel while losing the last Map of Infinity piece to Aggregor (Perplexahedron). 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 in right moments.
When seeing people getting hurt by his fault or because of his failures, Ben tends to get mad and acts much more violent and aggressive than he usually does. For example, when Overlord kidnapped Julie, or when Aggregor successfully absorbed the Andromeda Five, Ben went berserk and beat them up with all his strength, and, in Aggregor's case, to the point when Gwen was shocked and stopped him from beating up Aggregor more. Also, when Kevin mutated again shortly after stopping Aggregor, and temporarily went back to his psychotic way, hurting all the Plumbers' helpers, Ben became willing to kill Kevin by any means necessary. He began acting ruthless, aggressive, pessimistic, cold-hearted, nasty, and even ready to fight Gwen when she attempted to get in the way. Gwen, however, was eventually able to convince him to try another way as he was about to kill Kevin. During the episode, Ben confesses to Max he feels guilty for letting fame get to his head, and is trying to act more mature for once. Finally, in The Purge, when the Forever Knights are holding a large group of aliens hostage (and have killed some aliens already), Ben threatens to hunt the Forever Knights down for the rest of the lives if they don't let the aliens go.
Though often stated to be silly or unintelligent because of his immaturity, Ben is actually shown to be cunning and resourceful when needed, usually showing good adaptation skills when the Omnitrix doesn't provide him with the form he originally wanted. When he occasionally put his immaturity aside (most especially in the first two seasons of Alien Force), he's shown to be a responsible leader as well as a very competent fighter.
It's also evident that he is actually extremely smart in some respects, possessing advanced intuition, as in Where the Magic Happens where he memorised the writing for the secret true name of Ledgerdomain with just one glance, and in Perplexahedron, he figured out how the Perplexahedron works instantly. It was even stated by Gwen that he really isn't working up to his potential at school, and he replies, "That's what they tell me."
It's also pertinent to note that Ben has inherited both his paternal grandparents' personality. Although Ben inherited his grandmother Verdona's spirit, sense of humor, and overconfidence, he also inherited his paternal grandfather's determination, adventurous and self-sacrificing attitude. He is also as much of a practical joker, just like his paternal Anodite grandmother, Verdona.
Powers and AbilitiesEdit
Ben is the wielder of the Omnitrix (Prototype) (later the Ultimatrix and then the Omnitrix), 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-four aliens discovered (Ben 10, Ben 10: Alien Force, and Ben 10: Ultimate Alien, Ultimate forms 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.
Though he usually uses his alien forms to fight, there have been some occasions where he was taken for a real alien by others, humans especially (at least until his secret was revealed). At one point, he intentionally impersonated Bivalvan as Water Hazard to convince P'andor to go home, and though he was unsuccessful at convincing him, P'andor believed him to be Bivalvan.
In addition to the primary transformations and evolutionary function, the Omnitrix and Ultimatrix can both be used for various purposes. Both include an automatic translation system that allows Ben to communicate with most aliens that don't speak English.
During the Highbreed invasion, the Omnitrix displayed the ability to manipulate and repair genetic damage, a function he used to cure DNAliens and save the Highbreed from extinction. Azmuth also mentioned he can use it to bring back to life any species stored on Primus.
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 Perplexahedron, he is also shown to possess advanced intuition as he was able to understand how the cube-shaped planet Perplexahedron really worked with a small problem at first, but was then able to learn from that mistake and figure it out.
According to Azmuth and Paradox, Ben will have a glorious future.
Ben will be president in the future long enough to stop Vilgax from invading a third time, but then Gwen will take over and come back for a second term.
Ben is very calm about everything, even when the universe is at stake.