Despite being the "sister" race of the Green Martians, the two are polar opposites.
Eons ago, the White Martians savagely tried to take over the Earth. But, their peaceful counterparts, the Green Martians, trapped them in the Still Zone (Phantom Zone), for the choas they caused on Earth. Eons later, the White Martians escaped. Eight of their Martian leaders posed as superheroes, calling themselves the "Hyperclan". But, the Justice League figured out their plans and stopped them. Despite that their memories were erased and were turned into "humans", the Hyperclan tried to cause havoc, but the JLA stopped them and trapped them in the Still Zone.
Powers and Abilities
All the White Martians have flight, super strength, telepathy and the force-blasting "Martian Vision". They can also shape-shift. Some White Martians possesses unique abilities not possessed by the rest of the race. Like Green Martians, exposure to fire removes their powers.
The DC Comic Encyclopedia