Chronian

Chronians are (supposedly) a space-time traveling species from the planet Chronia.

Physiology
Chronians are outwardly indistinguishable from humans, except for older Chronians who have pale white skin and eventually develop brown marks around their eyes.

Chronians are able to halt and reverse time for individuals, and create purple glowing energy spheres for offensive attacks and activating the Hands of Armageddon. They are able to age humans to a zombie-like state and teleport. They are also able to control clocks and vehicles without physically touching them and have superhuman strength as evident with Ben as Eon breaking free from a chain and Eon throwing Ben at a large distance.

History
According to Eon, the misuse of his race's powers trapped their world and themselves outside time and space. When this happened, Eon came to Earth to activate a device called the Hands of Armageddon that would free the Chronians, but was captured by the plumbers and incapacitated via cryo-stasis.

Two centuries later, Eon escaped and aged his guardian to near death, eventually killing him. When Eon found the Hands of Armageddon, he tried to activate it but was to old to do so, so he tried to capture Ben Tennyson so that he can turn him into a younger clone of himself with his DNA in the Omnitrix, and Eon's DNA taking over Ben's personality.

Eon eventually succeeded and the Chronians were freed when Ben as Eon used the Hands of Armageddon to open a time rift between Earth and Chronia, but the Chronian invasion was sent back when Max Tennyson deactivated the Hands, and Gwen Tennyson managed to make Ben as Eon revert back to his personality. Upset at the event, Eon returns to get revenge on Ben, but he destroys Eon and the Hands of Armageddon as Wildmutt.

In truth, however, Eon was in fact a villainous duplicate of Ben Tennyson from a parallel future. Since being ejected from the Race Against Time timeline by the native Ben, Eon has abandoned his original agenda and resorted to attempting to rule the Multiverse with an iron fist.