Kelfour VI was the inhabited sixth planet of its star system.

During the Federation-Klingon War, on stardate 4789.6, a fleet of Klingon warships launched hypothermic charges at the planet. The subsequent explosions burned the atmosphere, resulting in the instant death of 11,000 civilians. (DIS: "The War Without, The War Within")

According to the revised edition of the Stellar Cartography: The Starfleet Reference Library ("History of the United Federation of Planets"), the Kelfour system was located in the Beta Quadrant.