Aggregor is a major secondary antagonist of the Xavier Xenoman series.


Aggregor resembles his canon Ultimate Alien appearance, but in the art-style of Omniverse and with slight alterations, such as neon-red eyes and a more shaven-looking head. After his defeat in Ultimate Alien and imprisonment in the Null Void, his clothes were left mildly altered and torn.

Personality and Past History

Much of Aggregor's personality and past history is identical to his variation from the original canon timeline, being a cruel, sadistic, menacing, and remorseless sociopath, who does whatever it takes to achieve his goals, fearing no-one and hungering for power. An artificial Osmosian who was granted the replicated mutant abilities energy absorption from Kevin's father, Devin Levin, Aggregor's main journey took place during the early events of Ultimate Alien, involving his capturing of five aliens, a Talpaedan named Andreas, an Orishan named Bivalvan, a Geochelone Aerios named Galapagus, an Amperi named Ra'ad, and a Prypiatosian-B named P'andor, where he'll use his abilities and a machine to transform the aliens into pure energy, allowing him to absorb their fullest power.

It was successful, transforming Aggregor into the unofficially-nicknamed Ultimate Aggregor, where he began the second phase of his plan: going throughout the universe in searches of the four segments of the Map of Infinity, which will lead him to the Forge of Creation, the out-of-universe birthplace of Celestialsapiens, and allow him to absorb the power of a Celestialsapien, particularly an infant one that lacks any extra personalities at its current age, which will allow Aggregor to not suffer said drawback. Even with Ben, Gwen, and Kevin's constant efforts, Aggregor was eventually successful, reaching the Forge of Creation and fending off the trio, along with a younger 10-year-old Ben. When young Ben suggests Kevin to absorb the prototype Omnitrix and regain his amalgamated form of mutated alien features he gained while he was an antagonistic 11-year-old in the original series, Kevin instead decides to go with the "A-game" and absorbs the energy of present-day Ben's Ultimatrix, transforming him in the powerful Osmosian mutation, labeled "Ultimate Kevin" that laid waste to Ultimate Aggregor and siphoning the five aliens' energy out of his body, albeit going in an insanity-influenced power trip afterwards. With Aggregor now defeated, he was arrested by Plumbers and imprisoned in the Null Void.

Throughout the events of Omniverse and prior to the events of the Xavier Xenoman series, Aggregor spent a year and a half fending off the monsters of Null Void, trying to keep his mind sane and hopefully find an escape. Rescued by Albedo, using Negative Ultimate XLR8's portal generation to access the Null Void, Aggregor was recruited toward Albedo's forces to battle against Ben and Xavier.

Powers and Abilities

Replicated from Kevin's father, Devin Levin, Aggregor possesses the mutant ability to absorb all forms of energy, even the bio-energy within creatures, to gain their physiology and abilities, which also includes Omnitrix aliens. Compared to Kevin, Aggregor is more skilled at his energy absorption, although lacks both him and his father's additional ability to absorb matter and transform their body into it.

Due to several years of practicing his energy absorption ability, Aggregor has a very strong immunity to suffering from a fractured, insanity-filled psyche when absorbing too much energy, represented while he was his Ultimate Aggregor form, although confirmed to be not absolute.


Aggregor possesses a mechanical spear, capable of firing blasts of red energy that can either disrupt any form of energy field, simply blast enemies in a fight, or even telekinetically lift and move objects via moving them with a electromagnetic aura of the red energy. After his defeat, the spear was not confiscated by Plumbers, as it was left back at Los Soledad, where Aggregor completed his Ultimate form transformation, and thus, Aggregor was able to reclaim and repair it.


Aggregor may not appear in every chapter of the series, similar to Albedo, but ones he does appear in has him have a majorly-important role, most commonly that of the main or secondary antagonist.


  • Aggregor is not an alien in the Xavier Xenoman universe, instead being mutants who are rarely called "Osmosians", purely being a condescending, falsely-extraterrestrial nickname coined by Servantis, mainly toward Kevin, a former member of his team, the Rooters.
    • Information such as the supposed Osmosian home-planet of "Osmos V" were purely-false information Servantis made up.
  • Aggregor was given brighter-red eyes to slightly differentiate him more from Albedo's similar eye color.
  • Aggregor's "Aggrebot" minions have all been destroyed, dismantled, and incinerated by Plumbers as of the beginning of the Xavier Xenoman series. Some surviving fragments and parts of them are in the hands of alien collectors.
  • Aggregor doesn't fully lack the ability of matter absorption, but simply isn't skilled enough to use said ability and has no desire to, as he considers absorbing energy more empowering.
Community content is available under CC-BY-SA unless otherwise noted.