Flaxan

The Flaxans are a species that originate from an alternate dimension that is parallel to Earth.

Biology
Flaxans are light-green humanoids, with dark eyes and two long antennas emerging from their heads. Due to time being much faster in their home dimension, when they try to interact with Earth's dimension for extended periods of time, Flaxans rapidly age until they expire. However after hundreds of years of technological advancements or what would be a few months on Earth, the Flaxans developed technology to compensate for the time differential to safety cross into Earth's universe.

History
The Flaxans were encountered by a team-up patrol by Omni-Man and Invincible. The Flaxans brought an entire army to attempt to conquer Earth. The two heroes intervened to stop them, and even though the Flaxans used overwhelming numbers, eventually they were forced to retreat as the invaders began to rapidly age. Before leaving the Flaxans abducted Omni-Man taking him back with them.

Omni-Man returned within a day on Earth, though the course of eight months had passed for him while in the Flaxan dimension. The hero claimed that Flaxans had enslaved him, but a week before he returned to Earth, he led a revolt against his captors and regained control of his powers, allowing him to fight back. Later he met with a team of scientists who were part of a rebellion and facilitated his return to Earth.

Some time after Omni-Man abandoned Earth after it was found out he had murdered the Guardians of the Globe and a Viltrumite spy sent to prepare Earth to be conquered, the Flaxans attacked Earth again, though this time were unhindered by the temporal side effects of being in Earth's dimension. The new Guardians of the Globe attempted to drive back the Flaxans but found themselves outnumbered. When the Flaxan commander announced that on behalf of the Flaxan Empire, Earth who pay for the transgressions against the Scourge of the Flaxan Empire, Invincible and Omni-Man, revealing that the latter was devastated their world when they tried to enslave him and were back for vengeance.

For them the Flaxans spent centuries plotting and scheming to conquer Earth, learning its language and studied Omni-Man's clothing to study the properties of his dimension. They finally developed the chrono-bands, devices that enabled them to counteract the side effects of rapid aging in Earth's dimension. As soon as the commander delivered his message, Invincible and the Guardians of the Globe began destroy the bands causing the invaders to age and turn to dust, forcing the survivors to flee back through their portal.

Culture
The Flaxan appear to a belligerent race, so focused on conquering Earth despite their many humiliating defeats.