L-374 IV was the uninhabited fourth planet in the L-374 system. This system was near and in the same sector as the L-370 system, and was near the Rigel system.
This was one of two planets destroyed in the planet killer attack of 2267; the other was L-374 III. The other two planets in the system, L-374 I and L-374 II, were spared. In 2267, Science Officer Masada of the USS Constellation picked up scans that the planet was being broken up by what was later known as the "planet killer". The captain of the Constellation, Commodore Matt Decker, ordered his crew to attack and destroy the machine. Despite their efforts, the doomsday machine destroyed the entire planet. (TOS: "The Doomsday Machine")
This planet was only mentioned in dialogue.