Where were you 45 years ago?
By the targs of Kahless, if you were down hanging around the "Arab City" of the Forty Acres backlot at Desilu-Culver, now known as the Culver Studios and about 6 miles southwest of "Desilu-Gower" (ie, Paramount Pictures), you would have been present for some true cinematic and galactic history. Namely....
The birth of the Klingons! (Otherwise known as Scene 33 from "Errand of Mercy"...)
Sure the script had been written for weeks, and it didn't air til March 23, 1967. But it was two months prior, on Friday, Jan. 27, that the Klingons really first came to life—on film, as intended, with John "One Step Beyond" Newland directing his one and only Star Trek, from Gene Coon's amazing dialog.
I wish I had a clip to put up here, but "documentary" might be being defined a little narrowly these days by the powers-that-be.
Just know that the outdoor pan that opens Act II was the very first time a Klingon appeared on camera; the next were the same-day follow-up citadel Scenes 38-41. They all fell on Day 2 of the six-day schedule; the late great John Colicos delivered his first lines as Kor, in his debut scene 34-35, the next working day, Monday—and throughout the remaining days of the shoot. It was Colicos who had the idea for the Klingons' "Genghis Khan" look, and makeup chief Fred Phillips took it and ran.
Jan. 27, 1967: Truly a day destined for galactic greatness ... and a headache of forehead canon from 1979-2005.