The Tellun system, or the Tellun star system, was an inhabited system in the Alpha Quadrant. It was located near the Federation-Klingon border. The two planets of the system, Elas and Troyius, were the homeworlds of the Elasians and Troyians respectively. During the mid-23rd century, the system was considered under Federation control, but the Klingon Empire also claimed jurisdiction. Tellun, the primary of the Tellun system, was located in the Alpha Quadrant on a star chart seen in the Star Trek: Discovery episode "Magic to Make the Sanest Man Go Mad" .