Xorda

The Xorda are a powerful and warlike race of aliens from Sonic the Hedgehog - specifically from the reality known as the "Archieverse", which is based on the comics produced by Archie as well as the Sonic the Hedgehog cartoon (known as SatAM by fans): the Xorda are responsible for destroying the human race and causing a global cataclysm that ultimately transformed Earth into Mobius and created the Mobian species - of which Sonic is part of.

Attack On Earth
At first the Xorda wished to offer humanity peace and sent an ambassador to make contact with them, however things were to take a terrible turn for the worse when a group of human scientists led by Dr Ivan Kintobor captured and disected the alien - this enraged the Xorda and in retaliation they utilised advanced technology known as Gene Bombs to effectively nuke the planet, devolving humanity into mutated beings known as Overlanders while also hyper-evolving the native animal species of Earth into Mobians.

Although the Xorda's attack was largely successful in wiping out humanity a small group of humans managed to survive the disaster and would make a safehaven in the hidden city known as Station Square - however following the great cataclysm Earth was lost and would be renamed Mobius.

These events were said to take place some time in the 21st century - almost 12,000 years before the main events of the Sonic comics: making the Xorda not only a powerful species but also ancient and although they left the planet shortly after the destruction of humanity they would eventually return and renew their assaults on the world..