Spectre of Earth-2
The Spectre
When murdered detective Jim Corrigan moves from his watery grave to the destiny "beyond", he is turned away and returns to Earth invested with almost limitless supernatural powers (first documented in More Fun Comics No. 52, Feb 1940: "Introducing the Daring Exploits of The Spectre!"). Now known as the Spectre, a ghostly green-hooded being that inhabits Corrigan's body and mind, he goes on to exact just revenge against evil actions and becomes a charter member of the Justice Society of America of Earth-2.
The Spectre vanishes from chronicles and returns decades later, apparently able to exist on such an ethereal plane that he can appear throughout the Multiverse and time.
Superman encounters the Spectre's power and vision when he tries to trace Supergirl after the destruction of Warworld. Apparently, Superman is traveling so fast that he is in danger of shattering the barrier to eternity itself, and it left to the Spectre and his master to make the Man of Tomorrow see his mistake (DCCP No. 29, Jan 1981: "Where No Superman Has Gone Before!").
