Benjamin Kirby"Ben" Tennyson, also known as Ben 10 is the wielder of the Ultimatrix. The Ultimatrix shapeshifting abilities allow Ben to become Alien X, a Celestialsapien.
Ben Tennyson in Ultimate Alien
He is actually 1/4 Anodite and 3/4 Human.
Powers[]
Ben wields the Ultimatrix (originally omnitrix) which give him shapeshifting powers that let him turn into any alien he wants, as long as they are in the Codon Stream.
Weaknesses[]
He can only turn into a alien when the Ultimatrix is charged. When he wielded the Omnitrix, Ben twists the dial to transform. This weakness was cured when Ben got the Ultimatrix.
Ben as Alien X
In the original series