In 2267, he informed the crew from the USS Enterprise that the Halkans would not allow the Federation to mine dilithium on their planet, out of fear that it might one day be used in acts of violence. Tharn reminded Captain James Kirk that he did have the power to take dilithium by force. Kirk told them to keep in mind that, while they did have such power, they would never use it. (TOS: "Mirror, Mirror" ) Tharn was played by actor Vic Perrin.