In the entire series of ben10 the it is Alien X, but just the ben10 Original series then it might be the 200 feet tall Waybig.
3 1st ben10 2nd ben10 alien force 3rd ben10 ultimate alien
no but he will return in the third series ben10 ultimate alien
ben10 isn't im not quite sure if there is more than one version, like if it is the alien force but i know ben10 isn't over
alien x is oiaa
no
its oiaa
nanemech
Cybo-Chip.
THE best alien of ben-10 ultimate alien is alien x.
== == its rame
the hive
NO