The people of the doomed Minaran star system represented by Gem, a mute empath whose willingness to sacrifice herself for others decided whether the Vians would rescue her species from a nova.
The Minarans are known through a single individual in the Original Series episode The Empath. The woman McCoy names Gem cannot speak, but she is a true empath: she can take another person's wounds and pain into her own body and then heal them, at real risk to herself.
In 2268 the star Minara is about to go nova. The Vians, an advanced race with the means to save the population of only one planet in the system, use an underground laboratory on Minara II to test whether Gem's people deserve it. They torture Kirk and McCoy to see whether she will give her life for a stranger.
Gem partly heals the dying McCoy before fear holds her back. Kirk argues that the Vians have lost the very compassion they are looking for, and they relent, restoring McCoy and leaving with Gem to save her world.