Vilgaxia (Classic)

Vilgaxia is the Chimera Sui Generis homeworld, as well as the home planet of Ben's archennemy Vilgax. It was first introduced in season 3 of Ben 10: Alien Force, and was then occasionally seen in some episodes.

Backstory
Vilgaxia was first introduced in Alien Force episode Ghost Town, where Ghostfreak, after having been freed from his jail by Vilgax, betrayed him and attacked the planet, possessing all inhabitants and turning them into Ectonurites slaves in few weeks. After several vain attempts to stop the infestation(including alternating the planet's sun constitution so its light would weaken Ectonurites), Vilgax escaped from the planet and reluctantly asked for Ben's help. Despite their differences, Ben accepted, and, after some complications, successfully freed the planet from Ghostfreak's control. As an agreement between them, Ben promised to not tell anyone this had happened, and Vilgax gained credit from Vilgaxia's population for saving them.

Appearance

 * Little has been revealed about Vilgaxia so far. The planet includes a large city with a large, fortress-like palace which serves as the home of Vilgax. Though Chimera Sui Generis are said in the original series(and it was confirmed by Dwayne McDuffie) as a warrior species, the planet is shown to include civilians.
 * It is shown that Vilgaxia has two moons.
 * Vilgaxia's insignia is very similar to the insignia of the terrorist organization HYDRA from the Marvel Universe, which bears a tentacled human skull.