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(CNN) -- With San Diego Comic-Con little more than a day away, a group of Klingons gathered at the Gaslamp Quarter trolley stop at 6 a.m. They watched as English signs were replaced with placards written with the Klingon language.
iReporter Chris Morrow, a serial Comic-Con attendee, got up early to take pictures of the Klingon hostile takeover staged by transit officials in San Diego, California, to promote the trolley system.
She's more of a Federation girl herself, but Morrow did buy a Klingon dictionary at a past Comic-Con and knows a Klingon when she sees one. This familiarity makes them a good choice, she said.
"Here at Comic-Con, it's the costumes," Morrow said. "I think because of 'Star Trek' and everything else with sci-fi on TV, that Klingons are something recognizeable. ... Whenever I see a Klingon, I can say, 'That's a Klingon.' "
If Comic-Con was one big Rorschach test, "Klingons" would probably be among the top words conjured. The fictional warriors, can frequently be seen prowling in costume or performing in groups. As ubiquitous as they are, Klingons helped drive the cultural symbolism that made "Star Trek" a cultural force and helped popularize the massively attended conventions that we now enjoy today.
Screenwriter and producer Gene L. Coon is usually credited for creating the species. Their first appearance, smooth foreheads and all, was in a 1967 episode of the original series of "Star Trek" called "Errand of Mercy." Captain Kirk's crew battles with a group of Klingons for the loyalties of the Organians. The truce at the end foreshadows later events in Klingon history.
Robert Thompson, a professor of television and popular culture at Syracuse University, notes that their appearance was almost "Oriental" and that these Klingons were a product of the Cold War mindset, symbolizing the conflicts with the then-Soviet Union.
"Star Trek" resonated with viewers because it played out social and political issues in the safe theater of science fiction. The show's popularity led to the start of "Star Trek" conventions in the early 1970s, which was about the same time as the first Comic-Con.
In 1974, a year after Comic-Con got its current name, the listed stars included Majel Barrett-Roddenberry and Walter Koenig from the "Star Trek" canon. The number of attendees and celebrities had about doubled and "Star Trek" was beginning to invade Comic-Con.
Klingons got a language five years later when "Star Trek: The Motion Picture" came out. The Klingons in the film uttered a few lines that were mostly gibberish conjured up by James Doohan. For future films, "Star Trek" producers consulted linguists to come up with language constructs. They stumbled upon closed-captioning linguist Marc Okrand by chance and picked him up to build a few Vulcan lines for "Star Trek II: The Wrath of Khan" and then to develop a language for Klingons in the third "Trek" film.
Okrand says he had to balance the need for an easy-to-learn language with something that is at once believable and foreign-sounding. He used statistical probability to create language constructs that are less commonly spoken in the human world.
Klingons evolved to take on Samurai and Viking warrior characteristics after the Cold War. By this time, they had more-advanced makeup designs and their foreheads had their bumpy appearance. To get over the hump of the makeup design change, a 2005 episode of "Star Trek: Enterprise" called "Affliction" attempts to give a back story by saying that a disease caused the appearance seen in the original series.
Star Trek's popularity peaked during the "Next Generation" era, in which the Klingons became friendly with the Federation. Costuming followed suit throughout the 1990s as Klingons' warrior ethic and culture was explored in greater detail.
Fast-forward to now: Director JJ Abrams' recent "Star Trek" interpretation earned about $385 million at the box office. But the movie omitted Klingons in favor of Romulans and a widely circulated deleted scene, included as a DVD bonus, left fans hoping the warriors would appear in a future film.
The Klingon characters have inspired an entire fan-driven cultural movement surrounding their language and mythological history. Beyond the countless action figures and costumes sold, Klingon-mania dominates conventions of various stripes.
Kevin Parker of Lawrenceville, Georgia, is one of many who likes to dress up as a Klingon and associate himself with a certain Klingon house. He knows a few phrases of the language and compares Klingons' popularity to the enthusiasm surrounding biker culture.
"Klingons are fun, the bad boys. Everybody loves to gravitate toward that group. The Federation is always clean and neat. The Klingons are like a gang of bikers. We cruise the galaxy looking for trouble."
Okrand says he's astonished at the passion people have shown for the Klingon language, going so far as to speak it fluently and perhaps know it better than he does. Entire Shakespearean works like "Hamlet" have been translated into their "original Klingon," in reference to a line in the sixth "Star Trek" film implying that the Bard's text has Klingon origins.
Okrand created entire Klingon dictionaries that sold hundreds of thousand copies over the years. The Klingon Language Institute sprouted up to foster development of the language and now has an estimated 2,500 members in 50 countries. In 2006's Guiness World Records, Klingon was listed as the fictional language with the most speakers.
Theater troupes perform plays in Klingon, and Okrand says he's currently helping out with a project to develop a full Klingon opera in The Hague, Netherlands, called "u." The opera will tell the story of Kahless the Unforgettable, the historical Klingon leader.
Klingon weddings take place at many conventions, borrowing on weddings performed in "Star Trek. Parker has been to many of these, including his own.
He says met his wife at a Klingon wedding at Dragon*Con in Atlanta in 2001. The couple met up the next year and married in their own Klingon wedding in 2003.