Omega IV

Facts

Primary: Omega
Class M
Inhabitants: Omegan
Known in the Klingon language as Qav'loS (TOS Novel: Forged in Fire)
- This is just Klingon for "final item in a list" (Qav) and "four" (loS)

c.late 2nd millennium: An ongoing war between the planet's two superpowers ends up collapsing planetary civilization following the release of the Omega IV virus. The native Omegans fall back to an Iron Age level of civilization. (TOS: "The Omega Glory")
c.2140s: The ECS Philadelphia visits to trade with the local populace. Seeing parallels in the Yangs' traditional beliefs and American democratic values, they provide reproductions of founding American documents to encourage them in their war against the Kohms. The crew of the Philadelphia dies from the Omega IV virus shortly after departure, while the artifacts are integrated into the Yang religion as further revelations from their deities. (DTI Novel: Forgotten History)
2248: The Jade Lady visits under the suggestion of Qagh, following his hearing reports of the Omega IV virus and its effects. He obtains a sample of the virus following this visit, and uses it as the basis for many future biogenic weapons. (TOS Novel: Forged in Fire)
2268: The crew of the USS Exeter are wiped out from the Omega IV virus, leaving Captain Ronald Tracey as the only survivor. He is recovered from the planet following the subsequent investigation by the USS Enterprise. (TOS: "The Omega Glory")