Earth-4
From Multiversal Omnipedia
Earth-4 was one of the "infinite Earths," only revealed to the other worlds shortly before the Crisis on Infinite Earths. Its champions included Blue Beetle, Captain Atom, the Question, Thunderbolt, Nightshade, Peacemaker and Judomaster. During the Crisis, a power-amplified Psycho-Pirate inspired paranoia in the planet's inhabitants, but it didn't stop Harbinger from pulling it into the netherverse created by the slain Monitor.
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Post-Crisis, Post-Zero Hour
After the Crisis, Earth-4 merged with the other four surviving Earths to form the new "Earth-Sigma."
