The inhabitants of Vendikar, a world first settled from Eminiar VII, who fought a five-century war against their parent planet entirely by computer, with real citizens reporting to be killed as the casualties were tallied.
The Vendikans are the people of Vendikar, the third planet of the Eminiar star system, described in the Original Series episode A Taste of Armageddon. Their world began as a colony of Eminiar VII but grew into a bitter rival.
For roughly five hundred years the two planets waged war without firing an actual weapon. Attacks were simulated by linked computers, and those listed as dead were given a day to walk into disintegration chambers. The arrangement preserved cities and culture on both sides, which is exactly why the war never ended.
No Vendikan is seen on screen. In 2267 a Vendikan strike declares the Enterprise destroyed, and Kirk responds by wrecking the Eminian war computers, breaking the treaty and leaving both worlds facing genuine bombardment. Ambassador Robert Fox stays behind to help them negotiate peace.