Star Trek has never known exactly what Klingons look like, until now (maybe)

polygon.com:

Apart from the benevolent pointy-eared Vulcans, there’s no fictional alien species more iconic than the Klingons — not only in Star Trek, but in pop culture at large. The spacefaring warriors have evolved over half a century from generic Cold War antagonists into a complicated and spiritual culture that evokes both medieval Vikings and feudal samurai. There is a complete, functional Klingon language studied and spoken by fans around the world, who routinely don the familiar armor and forehead ridges at fan conventions. Most people who are even casually familiar with Star Trek would recognize a Klingon should one pass by on the street (perhaps in Las Vegas, this or any August), and even applaud the remarkable accuracy of their makeup and attire.

And yet, there is not, nor has there ever been, one definitive Klingon makeup design. Despite fan uproar practically every time a substantive change is made to the craggy foreheads and wispy beards of the space conquerors, their look has been in flux from the beginning, and will likely continue to evolve along with the production technology behind Star Trek itself. In honor of the return of a more familiar appearance in the season premiere of Star Trek: Strange New Worlds, we’ve taken a deep dive into the rocky history of science fiction’s most famous forehead, from 1966 to today.

The Klingons were introduced during the first season of Star Trek, in the 1967 episode “Errand of Mercy.” Writer/producer Gene L. Coon used the story’s conflict between the United Federation of Planets and the rival Klingon Empire over a non-aligned planet as an allegory for Cold War proxy conflicts, but — according to the exhaustively researched book These Are the Voyages: TOS, Season One by Marc