The Star Trek Actor Who Spoiled Spock's Death Before Wrath Of Khan Even Began Shooting
The decision to kill Spock (Leonard Nimoy) at the end of the 1982 feature film "Star Trek II: The Wrath of Khan" was made quite early in the production process. It's a matter of record (in "Star Trek" magazines and the like) that a script written in April of 1981 already had Spock's death as an established part of the story. Indeed, there was an early draft wherein Spock would perish early in the film, and the climax would elapse without him. Actor Walter Koenig, who played Pavel Chekov in the movie, once commented on this early script, saying that it was his idea to move Spock's death to the end. Many of the writers agreed with Koenig's assertion, and Spock's death was moved to the film's climax. It just made more sense.
Fans weren't necessarily shocked by Spock's death, however. Spock's death had been leaked to the press very early on, with newspapers talking openly about the plot without worrying about spoilers. Indeed, the spoiler was so well-known that, prior to the release of "Star Trek II," Robin Williams was already making jokes about Spock's death on "Mork & Mindy."
"Star Trek II" writer/director Nicholas Meyer didn't leak the news, of course, and the scripts weren't being published on the nonexistent internet, so how did Trekkies come to know that Spock was going to die? It seems that it was Koenig again. In the August 31, 1981 issue of the Philadelphia Enquirer, it was reported that Koenig, perhaps in a moment of loose-lipped pique, accidentally let slip that Spock's death was forthcoming. Or perhaps he simply had no issue with spoiling the ending. Regardless, knowledge of Spock's death proliferated. By the time "Star Trek II" came out in June of 1982, everyone knew.
Walter Koenig spoiled Spock's death
Weirdly, no one got on Koenig's case (at least not in a career affecting way) for talking openly about the end of "Star Trek II." Indeed, a Kansas City Star article from May of 1982 (preserved on the Collecting Trek website) reported openly on Spock's death after a screening at a recent "Star Trek" convention in Kansas City. The reporter and a room full of Trekkies got to see a sneak peek of the movie a few weeks early, and the ending was spoken of openly ... and in glowing terms. Yes, it seems that Spock's death was a good idea. It's a pity that everyone knew about it so plainly. There was, it seems, never any shock about the matter.
Nicholas Meyer talked a little bit about the Spock spoiler on the "Star Trek II" DVD commentary track, and he revealed that, yes, there was an early version of the script wherein Spock died partway through the movie, a script that was written by Jack B. Sowards, who ultimately took the screenplay credit on the movie. He said that part of the impetus for moving Spock's death to the end of the movie was because of the leak. He said on the commentary that the script had leaked, but he could also have been alluding to Koenig's loose lips. His response to the leak was to move Spock's death to the end ... just like Koenig had suggested.
So it seems that Walter Koenig caused the tempest-in-a-teapot over the spoilers, but had also thought up a solution to the script when it was needed. Koenig, then, was instrumental to the success of "Star Trek II."