Atomix is an alien obtained by a future Ben Tennyson in an alternate timeline, he is first mentioned in the episode "Ken 10".
There is not much known about him, but we do know that Atomix is one of the 10,000 aliens on the Omnitrix of Ben 10,000. Atomix was mentioned by Ken Tennyson while he looked through his Omnitrix (Ken didn't get it, much to his disappointment). He comes from the same planet as Alien X, but a different race of the species. He is a radioactive alien who shoots out microwave blast from his hands making him one of Ben's most powerful aliens. But can give people radiation poisoning if he gets too close our touches a them.