Ditto

He is one of Ben's original aliens. He is used by ken a lot also. He is a Splixson from Planet Hathor.

Appearance
Ditto is a small, humanoid alien with the ability to clone himself without limit. Every clone operates independently, regardless of whether or not Ben wants them to, and each clone is indistinguishable from the others. Though the clones are autonomous, they share each other's pain, and the death of one clone will cause the death of the rest (as seen with Dr. Animo's Ditto-enhanced Stinkfly mutants) which negates the usefulness of making large numbers of clones. The child-size Ditto is also no stronger not faster than his size and build suggests.

Planet
The planet Hathor is home to a race called Splixsons who have grown out of Mitosis (that is how they can divide without limit), but they don't fight or start wars at all (that was made clear in Divided We Stand) because of this they are more peaceful than other races and they tend to be farmers or painters because of it.

Omni-World
Ditto is one of the main characters in Omni-World. He, along with Eye Guy, are the two main characters who along with the rest of the cast, often get into trouble or just have silly adventures.

Ben 10 Fiction Ultimate Alien
Ditto make his re-appearence in The Peerment

Dan 10:Time Warrior
Ditto makes Dan's 11th alien when he was sent back in time to ancient Hathor.