The Tenebrous Cluster was an astronomical phenomenon encountered by the USS Voyager in 2373, on stardate 50716.5. Voyager traveled through the Tenebrous Cluster from stardate 50718.4 to 50722.0, where they encountered a humanoid starship captain named Uthlow, and a race of malevolent non-corporal beings known as Monthuglu. (VOY - Strange New Worlds I short story: "Monthuglu")