L-374 IV was the uninhabited fourth planet in the L-374 system. This planet was located within a sector of the Beta Quadrant and was near the L-370 system. This planet was close to 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.
The quadrant of origin for this planet was inferred from the trajectory of the planet killer. This ancient machine destroyed, in this order, L-370 and L-374 and the next system targeted was the Rigel system. This system had been established to be in the Beta Quadrant by star charts seen in Star Trek: Enterprise, Star Trek: Discovery, Star Trek: Picard, Star Trek: Strange New Worlds, and Star Trek: Section 31.