- "We fought back. We'd known war. But not like this. White Martians had been toiling underground, building weapons of death. Fire traps. Their technology overwhelmed us. There was no honor in how they fought. They herded us into camps. I swore no matter what, I would protect my family. We would survive. But when we got through the gates, they took the women and children. Men were forced into labor. The others went to the furnace. My wife and daughters burned. I escaped. I survived. To my great shame. I will hear my family's screams until the day I die."
- ―J'onn J'onzz
White Martians are a particular breed of Martian featured in comic books published by DC Comics. They first appeared in JLA #1 in January, 1997. White Martians are cousins to the Green Martians and are distinguished from them by their albino skin pigmentation, their tapered heads, angular bodies and large claws and teeth. White Martians are a sentient race, but are also known as ruthless predators. They are sworn enemies of the Green Martians. Both races are adept shape-shifters, capable of assuming any form they please (given a relative size and mass).
White Martians made a brief appearance on the CBS television series Supergirl in the episode "Strange Visitor from Another Planet", directed by Glen Winter, which first aired on January 25th, 2016. They were presented in similar fashion to their comic book counterparts, and were revealed to have been a subterranean race, who rose to the surface and wiped out nearly all of their green cousins. J'onn J'onzz, one of the last of the green Martians watched his family burn to death in the fires before successfully escaping the holocaust and coming to Earth.
One White Martian arrived on Earth and used its shape-shifting powers to assume the identity of Senator Miranda Crane. Through Crane, it publicly elevated anti-alien hysteria amongst the general public, all as a ruse to lure out J'onn J'onzz. The plot worked and the two Martians battled one another, but J'onn proved victorious with the aid of his comrade, Kara Danvers, aka Supergirl. 
When Non orchestrated the release of many of the D.E.O. prisoners, he deliberately ordered the White Martian to remain in confinement.