Blackout Boy/Graah

From Who's Who in the Legion of Super-Heroes 1:

One of three spies from the planet Murra who were sent to scout Earth in preparation for its invasion, Graah took a pill developed on his home planet which would give him the temporary super-power to cause total darkness in any area. Using this ability, he joined the Legion in hopes of learning their secrets. Instead, Blackout Boy, as well as his comrades had walked into a Legion trap. The Legionnaires followed the Murran spies to their homeworld and destroyed the machine that manufactured the super-power pills, ending the invasion threat.