Following the successful revival of the Flash in Showcase #4 (Oct. 1956), a new Green Lantern was introduced in Showcase #22 (September–October 1959).
This Green Lantern was Hal Jordan, a test pilot who was given a power ring by a dying alien, Abin Sur, and who became a member of the Green Lantern Corps, an interstellar organization of police overseen by the Guardians of the Universe. The Corps’ rings were powerless against anything colored yellow, due to a yellow-colored “impurity,” or “dopant,” in the master power generator located on Oa, where the Guardians maintained their headquarters; the yellow dopant was described as being a “necessary” one, for without it, the master generator could not function as such.
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