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- Xan - Living electromagnetic beings, thrived in the earliest era on Krypton.
- Xanadorans - Humanoid race and home to Star Sapphire Dela Pharon. Recently she has looked more alien, with darker skin and a more alien-like complexion.
- Xanthuans -
- Xenoformers - The Xenoformers from Galaxy X are Grant Morrison's bizarre meld of the Transformers and Scoop from Bob The Builder. Currently a Xenoformer named Metalek is imprisoned in Britain's Basement 101.
- Xenusians - The Xenusians were a race of malevolent aliens who spread a mysterious plague that caused the victims to mutate and transforms into new Xenusians. Also, the Xenusians were responsible for the annihilation of the entire Vexaphon race.
- Xudarians - The Xudarians of Xudar are an orange skinned species of extraterrestrial pseudo-avians. Their most respected representative is Tomar-Re of the Green Lantern Corps.
Read more about this topic: List Of Alien Races In DC Comics