A proud, honour-bound people whose empire went from the Federation's fiercest rival to its most important ally.
The Klingons are a warrior people from the planet Qo'noS, whose culture prizes honour, combat and loyalty to family. Their empire is governed by the High Council, led by a chancellor, and their history and religion look back to Kahless the Unforgettable, who united the Klingons long ago. Their language, food, opera and weapons such as the bat'leth are all distinctive.
The Klingons were the main rivals of the Federation in the original series, and the two powers came close to war several times. Their appearance has changed over the years, and Enterprise explained the smooth-headed Klingons of the original series as the result of a genetic plague. In Star Trek VI, the explosion of the moon Praxis forced the Empire to seek peace, which led to the Khitomer Accords.
By the twenty-fourth century the Klingons were Federation allies, and Worf served in Starfleet. The alliance was strained by the Klingon civil war and Gowron's invasion of Cardassia, but held through the Dominion War, after which Worf served as Federation ambassador to Qo'noS and Martok became chancellor.