Ditto

He is Other Alien not in 1st ten

Splixsons are low on the food chain on their planet and have developed the ability to split themselves to avoid predators.Ditto is a Splixson from the planet Hathor. He is a small, humanoid alien capable of cloning itself without limit. Every Ditto can operate independently, but pain felt by any one Ditto is transmitted to the rest, and the death of one Ditto will result in the death of every clone. If one or more Ditto clones are isolated from each other when the Omnitrix times out, the timer will reset and Ben won't revert back into human form until they are reunited. This only seems to apply when a Ditto is physically unable to reunite with the others; in open air, the Ditto clones will float to each other over great distances in order to facilitate the transformation.