Benjamin Kirby "Ben" Tennyson was a normal ten-year-old kid until he found the Omnitrix, a powerful watch-like device that allowed him to turn into ten different aliens. Though initially immature and clumsy, Ben grew to be 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 been deputized by the Plumbers and gained more aliens as time progressed.
Ben is one of the strongest starter characters, and he is the main hero in the story. His Signature Attacks are 5 of his aliens who provide Ben awesome power and range.
- Neutral: Double Punch Kick - Does a jab, cross, then a right-legged kick.
- Running: Soccer Strike -
Rushes forward with an upright sliding attack.
- Up: Upper Punch - Swats his fist above him.
- Down: Sweep Kick - Sweeps the ground with both legs.
- Charge Attack Side: Scoring Shot - Does a turning back kick with a green aura.
- Charge Attack Up: Tennyson Upper - A powerful hopping uppercut.
- Charge Attack Down:
- Aerial Neutral:
- Aerial Side: Midair Soccer Swing - Swings his leg upwards in a spinning kick motion.
- Aerial Up: Reverse Bicycle Kick - Does a forward flip kick.
- Aerial Down:
- Neutral: Swampfire - Turns into Swampfire briefly to lob 2 Fireballs that each does 10% of damage.
- Side: Humungosaur - Turns into Humungosaur briefly; charges at the opponent with a shoudler ram, then flings upward to finish the charge. Each attack connecting does 12% of damage.
- Up: Big Chill - Flies up as Big Chill into the air and drop 5 ice shards which do 13% of damage.
- Down: Ampfibian - Creates a brief electrical field around himself as Ampfibian. Each shock does 6% of damage.
- Punch Time Explosion: Ultimate Humungosaur - Ben transforms in Humungosaur, then using the Ultimatix transforms into Ultimate Humungosaur. Ben/Ultimate Humungosaur then fires a barrage of 10 Bio-Missiles that destroy all enemies that get in his way.
- Synergy: Fred Fred Burger is Ben Tennyson's synergy attack. He appears eating nachoes and farts everywhere. Ben then turns into Swampfire and takes an unpleasant whiff of the scent, showing distaste. He then ignites Fred's fart clouds. This creates massive explosions which damages opponents in range.
- Born in December 9th, 1996.
- Ben Tennyson (Teenage) is one of the few characters to maintain their original voice actors for both the 3DS version and the console version.
- The others being Ben Tennyson (Young), Mandy, Bubbles, Him, and Bloo.