Image: Paramount Pictures
Star Trek II: The Wrath of Khan was a success on the strength of its villain. But the William Shatner wasn't sure a returning series villain was such a good idea.
Talking to IGN to promote the 35th anniversary celebration of the film, Shatner shared that he didn't want to look to the series for inspiration at all for Star Trek II.
I recall that they began to talk about the second movie, and the talk began to be about what segment of the 79 [TV episodes] that we shot would be useful. And I kept saying, why do we want to go to a segment? Why don't we invent something absolutely new? And the people in charge were much more aware than I was that the fans would be more sympathetic to… [it] would be a better vibration if it echoed a popular hour from the series, and make that, and then further the story as a film. And they were absolutely right that there was a ramification doing it that way, and the fact that the actor [Ricardo Montalban] was able to repeat his role was another singular advantage.
It's lucky that Shatner didn't get his way. Montalban's performance in that film is timeless, and the conflict between Kirk and Khan is one of the best character beats in all of Trek.
In my opinion, Star Trek isn't flush with all that many compelling interpersonal conflicts, especially not with regards to villains. There are great characters, absolutely, but plotting often tends to push more conceptual than personal, toward big scifi ideas and away from psychological motivations on the part of the cast. Which isn't necessary a criticism! But it's part of why Khan sings here, and why he's such a memorable presence in Star Trek II. He offers something we don't see much in the franchise.
Anyway, we can be glad Shatner got overruled by writer/director Nicholas Meyer and crew. Pity the same couldn't be said for Star Trek V.