Monac IV was the fourth planet of its star system, in Cardassian space. It was where the Cardassian/Dominion Monac shipyards were located.

In 2375, the Monac shipyards were a crucial production facility for the Dominion effort to retake the Chin'toka system. A Klingon fleet launched an attack on the shipyards, but were repelled with casualties estimated at 30%. (DS9: "Image in the Sand")

Shortly after, the Klingon Bird-of-Prey IKS Rotarran, under the command of General Martok, destroyed the shipyards by triggering a solar flare that engulfed the installation. (DS9: "Shadows and Symbols")

According to Star Trek: Star Charts (p. 46) and Stellar Cartography: The Starfleet Reference Library ("Stellar Cartography", p. 18; "Federation Historical Highlights, 2161-2385"), the Monac system was located in the Alpha Quadrant. The primary was a K-class star. According to a map of the Cardassian Union – prepared by an anonymous astrography clerk, from the Cardassian Central Archives, in 2364 – Monac was identified as a Cardassian system.
According to the Star Trek Encyclopedia (4th ed., vol. 2, p. 50), Monac IV was probably named for Star Trek: Deep Space 9 special effects supervisor Gary Monak.