Chronian

The Chronians were a subspecies of Humans from an alternate version of Earth known as Chronia who are capable of traveling through space and time.

Anatomy
Being a human subspecies, the Chronians were mostly indistinguishable from humans except for their skin being pale white and forming brown marks around their eyes as they age.

Powers and abilities
The Chronians were able to halt and reverse time. They can also travel through time and space by either using portals or teleporting.

The Chronians can fire powerful beams of purple time based energy from their hands that are able to instantly age ordinary humans to a zombie-like state.

The Chronians' time rays can also age other beings such as To'Kustars, regular and evolved Methanosians and Atrocians to the point of crumbling to dust.

Similar to the Osmosians, the Chronians were stronger and more agile than ordinary humans.

The Chronians were durable enough to withstand the Pyronites' fire blasts, the Petrosapiens' projectile shards and the Vulpimancers' tackles with no visible damage.

The Chronians' time powers grant them limited molecular manipulation abilities, allowing them to create illusions and mirages.

The Chronians' time energy can become electrical allowing them to manipulate and control technology and machines such as vehicles or clockwork gears.

According to Professor Paradox, the Chronians were able to sense the ripple effect in time when a Chronosapien uses their time powers.

Weaknesses
Though very powerful, the Chronians' powers can backfire on them if misused. It would also seem that overusing their powers can weaken them and speed up their aging process.

The Chronians' time rays were useless against anything diamond-related such as the Petrosapiens since they do not age. They were also ineffective against gumballs.

Like other organic beings, the Chronians can be erased from existence by a Chronosapien Time Bomb or banished to another timeline by an normal Chronosapien.

The Chronians do not have the same level of enhanced reflexes as evolved Methanosians. They can also be lifted by a species with as much strength as the Chimera Sui Generises.

Culture and society
The Chronians appear to be very greedy with their space-time powers as their once-beautiful world was ruined by their abuse of power.

The Chronians also seem to be unaware of the full consequences of manipulating time and space as they wound up stuck in another dimension in their haste to escape the effects of time.

History
Eon was an alternate version of Ben Tennyson who had become corrupt and evil after something bad happened to his Omnitrix. He traveled through various different timelines, enslaving their native version of Ben and turning them into his personal servants with the intention of becoming the one and only Ben Tennyson in the entire spacetime continuum.

Eon made his way to the Race Against Time timeline to activate a device called the Hands of Armageddon before being captured by the Plumbers of that universe. Assumed to be an alien, Eon was placed in cryogenic freezing but eventually broke out 200 years later and aged his guardian to near-death.

When Eon found that he was indeed too old and weak to activate the Hands, he set about capturing the timeline's native Ben with the intention of using his Omnitrix to turn the boy into a younger version of himself. This was because the Hands of Armageddon needed the energy of a younger being of his power to activate it. To ensure that Ben would permanently become a clone of himself, Eon also deactivated the Omnitrix's failsafe so that his DNA would completely overtake Ben's personality.

After multiple failed attempts, mostly due to interference from Plumbers, Eon was finally able to capture Ben, his cousin Gwen, and their grandfather Max. Holding them captive, Eon revealed himself to be Ben's future self, which Max admitted to. Eon then activated the Omnitrix, turning Ben into a younger Eon. Due to his powers over matter, Eon was able to retain his personality in the DNA sample that was collected in the Omnitrix. Upon succeeding in this goal, Eon seemingly wiped himself from existence.

Ben as Young Eon activated the Hands of Armageddon, but his Human personality retook control when Gwen managed to reach Ben, prompting him to revert back to Human. When Max deactivated the Hands, an enraged Eon returned and tried to exact his revenge. However, Ben as Wildmutt managed to send Eon crashing into the Hands of Armageddon, destroying it and inadvertently sending Eon out of that timeline.

Eon made his way to an alternate timeline inhabited by a version of Ben's future self Ben 10,000 who he tricked into sending him to the Prime Timeline using Clockwork's time rays. He used the Prime version of the Hands of Armageddon and the Ultimatrices used by both Ben Prime and Ultimate Ben to cross over. He revealed his true identity after Gwen Prime immobilized his army using a magic spell.

However, Eon's plans were foiled when Ben Prime as Jetray destroyed the Hands, effectively ridding the Multiverse of the Hands forever and undoing Eon's actions. Since his defeat, Eon has abandoned his original agenda and resorted to attempting to rule the Multiverse with an iron fist by any means necessary.