Chronian

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

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

Abilities
Chronians are able to halt and reverse time, and can travel by means of teleportation.

Chronians can create purple glowing energy spheres for offensive attacks and activating the Hands of Armageddon. They can fire powerful time beams that can age organic beings to either a zombie-like state or the point of crumbling to dust.

Chronians are able to control clocks and vehicles without physically touching them.

Chronians possess enhanced strength, as evident when Eon threw Ben across a large distance while Ben's Chronian form broke free from some chains.

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 this event, Eon returns to get revenge on Ben. However, Ben destroys the Hands of Armageddon by knocking Eon towards it as Wildmutt.

In truth, however, Eon was in fact a villainous duplicate of Ben from a parallel future obsessed with becoming the only Ben Tennyson in existence. 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.