Developed by screenwriter Gene L. Coon in 1967 for the original Star Trek (TOS) series, Klingons were swarthy humanoids characterized by prideful ruthlessness and brutality. Klingons practiced feudalism and authoritarianism, with a warrior caste relying on slave labor. With a greatly expanded budget for makeup and effects, the Klingons were completely redesigned for Star Trek: The Motion Picture (1979), acquiring ridged foreheads. In subsequent television series and in later films, the militaristic traits of the Klingons were bolstered by an increased sense of honor and strict warrior code similar to those of bushido.
Klingons are recurring antagonists in the 1960s television series Star Trek, and have appeared in all subsequent series, along with ten of the Star Trek feature films. Initially intended to be antagonists for the crew of the USS Enterprise, the Klingons became a close ally of humanity in Star Trek: The Next Generation. In the 1990s series Star Trek: Deep Space Nine, humans and Klingons join with the Romulans to fight the Dominion.