Mithren was a inhabited planet in the Delta Quadrant, located near Bothan territory.
Neelix had some contacts on Mithren, who informed him in 2372 that they had lost a number of vessels to the Botha. (VOY: "Persistence of Vision") The starship USS Voyager remained in contact with Mithren for some time, up until a month prior to stardate 49485. (VOY: "Investigations")
According to the Star Trek: Star Charts (pg. 82), Mithren was located in the Mithren system. The Mithren system was located in or near space claimed by the Haakonian Order. This system was a single star system. Primary was a Class M star with a magnitude of +9.