Back in the 90s DC decided that the resident Green Lantern, Hal Jordan, was out of touch with the youth of the day. So they decided to get rid of him, by making him go crazy with grief. After the villain Mongul destroyed Coast City, Hal went nuts and rampaged through the universe killing the entire Green Lantern Corps as well as the Guardians of the Universe. Convinced that he could resurrect the population of Coast City, he absorbed the energy of everyone he killed and became the evil Parallax. Eventually Parallax was redeemed during the Final Night story arc, where Hal Jordan gave his life in order to save Earth from a sun eater (don't ask). Fast-forward ten years later to Geoff Johns Green Lantern reboot, and he retcons the whole thing: it turns out that Hal never went crazy. Rather, Hal was processed by giant yellow space bug called Parallax that just so happens to be the personification of fear thereby re-redeeming the character once again. So yeah, be careful about those space bugs kids theyll drive ya nuts.