The Children of the White Lobe are a race of mutants, considered to be a fanatical religious cult in the DC universe.
Their purpose is still rather mysterious, but as shown during the events of the Sinestro Corps War they are powerful enemies. According to dialogue between two of the Green Lanterns, they can manipulate will-power constructs not unlike the Lanterns themselves, shown when they are seen creating a force fields around themselves and attacking and killing Green Lanterns with their powers. They also can generate devastating explosions with their will-power, and were being used by the Sinestro Corps as the trigger for the planet destroying "blink bomb" set to be detonated in Mogo's core.
After the Sinestro Corps' defeat, the Children present were either captured or killed, indeed Kilowog killed one of them himself. The Guardians are currently mulling over the idea of wiping them out, allegedly.