While the Green Lanterns and their allies fight earthbound as well as cosmic crime, some villains are worse than others. Between evil Lantern corps, bloodthirsty supervillains, and galactic evil scientists, the Emerald Knights work hard to ensure no evil escapes their sight.
First the greatest of the Green Lanterns and then their greatest enemy, Sinestro remains one of the DC Universe's most enduring antagonists. After becoming a Lantern to further instill order over the galaxy, Thaal Sinestro put his homeworld of Korugar under his own totalitarian control.
It was only when Sinestro's protégé Hal Jordan exposed his work to the Guardians that Sinestro was removed from the Corps.
Since then, Sinestro menaced the DC Universe as a Legionnaire of Doom and the founder of the Sinestro Corps, harnessing the yellow energy of fear. Although Sinestro occasionally commits noble acts, his hatred, anger, and desire for power ultimately define him.