Supervillain in DC Comics. Controls the entire electromagnetic spectrum (despite the name). Most recently a member of the first incarnation of the Injustice Gang (the traditional archenemies of the JLA) to be led by Lex Luthor.
There was (and still may be, I'm not sure) a Japanese female superhero going by the name of Dr. Light. I think she may have been killed during the Darkness Within/ Eclipso thing. Someone wanna help me out with that?