The head of the Halkan Council, a committed pacifist who refuses the Federation the right to mine his planet's dilithium, and whose mirror universe counterpart faces annihilation for the same refusal.
Tharn leads the ruling council of the Halkans, a people whose history contains no violence and who are prepared to die rather than see it begin. He appears in the second-season Original Series episode Mirror, Mirror, played by Vic Perrin.
In the opening scene Kirk asks for permission to mine the planet's rich dilithium deposits. Tharn accepts that the Federation is peaceful at present but will not risk the crystals one day being used to take life, and he declines even while acknowledging that the Enterprise could simply take them by force.
After an ion storm sends Kirk's party into the mirror universe, they meet Tharn's counterpart, who gives the same answer to the Terran Empire knowing that it means the destruction of his people. Kirk stalls the order to fire on the Halkan cities for as long as he can.