The Klingons (ˈklɪŋ(g)ɒn ; Klingon: tlhIngan ˈt͡ɬɪŋɑn) are a fictional species in the science fiction franchise Star Trek. 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, and is reminisant of Ancient Sparta. 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 honour and strict warrior code similar to those of bushido, and a view of the afterlife similar to the Ancient Scandinavians. 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. Among the elements created for the revised Klingons was a complete Klingon language, developed by Marc Okrand from gibberish suggested by actor James Doohan. Spoken Klingon has entered popular culture, even to the extent that some of the works of William Shakespeare and parts of the Bible have been translated into it. A dictionary, a book of sayings, and a cultural guide to the language have been published. According to the Guinness World Records, Klingon is the world's most popular fictional language as measured by number of speakers. The Klingons were created by screenwriter Gene L. Coon, and first appeared in the Star Trek episode "Errand of Mercy" (1967). They were named after Lieutenant Wilbur Clingan, who served with Star Trek creator Gene Roddenberry in the Los Angeles Police Department.