The Klingon Empire is one of Star Trek's weirdest alien civilizations, if only because its characterization has changed so drastically over the years. The Original Series depicted the Klingons as scheming and duplicitous, while later shows like Star Trek: The Next Generation transformed the Empire into an honor-bound society of warriors. However, the prequel series Star Trek: Enterprise attempted to explain this discrepancy with a plot about genetic engineering, suggesting that mutations had caused the Klingons' appearances and mindsets to change.