Multiple realities
(covers information from several alternate timelines)

Tharn, a Halkan

The Halkans were a humanoid civilization with the unusual quality of having a history of total peace. In 2267, the Halkans refused to open negotiations with the Federation to allow the Federation to mine dilithium from their planet, out of fear that the Federation would one day use their materials for acts of violence.

Tharn in the mirror universe

The Halkans of the mirror universe were also a peaceful race, who preferred to die rather than allow their dilithium to be taken by the Terran Empire. (TOS: "Mirror, Mirror")

This appears to be one of the rare examples of races being virtually identical in both universes.

List of Halkans

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