The Madillon Cluster was a star cluster in which the Sontarans and the Rutan Host fought one of the battles of their war. (TV: The Two Doctors) Samur was located in the Madillon Cluster. (AUDIO: Heroes of Sontar)
The Madillon Cluster was one of the possible places that the Sixth Docotr speculated to be a possible location of dormant cybermen after the Great Cyber War. (AUDIO: Last of the Cybermen)