Psi-Virus

The psi-virus was a virus-like energy transmitted, like a true virus, from mind to mind. Created by Saraar and transmitted to Earth by the Infektikon, the psi-virus harnessed the evil and aggressive impulses in its victims. It then infused those traits into their shadows, which became animated with a murderous life of their own. The shadows would slay their hosts and send the aggression back to Saraar's machine. The psi-virus' victims were saved by the second Flash and Green Lantern (Hal Jordan), who were infected themselves but managed to defeat their shadows.