Why did Kirstie Alley not have the role of Saavik in the Search for Spock?

Answer 1

Here's a quote from producer/director/star Leonard Nimoy that gives his side of the story:

"It looked like everything would work out, so when the script was ready, we sent it along for Kirstie and her agent to read. Shortly thereafter, her agent called us back and said, 'Look, we didn't realize how large a roll Saavik was going to have in this film. So we're withdrawing our earlier figure. Here's what we have to have now. . . .' and he quoted a price that was so far beyond our reach that it left me slack-jawed. I'm sure neither he nor Kirstie realized it, but the salary he wanted for her second Star Trek appearance was higher than what was being paid to DeForest Kelley after seventeen years."

Alley claims that they offered her less money than what she got on Star Trek II.

The role was re-cast and actress Robin Curtis made her film debut as Saavik in Star Trek III: The Search For Spock.

Answer 2

She demanded she be paid higher than DeForest Kelley. Nimoy told her would not do that to the man who played McCoy for 20 years, so she refused to come back. Nimoy has reported the discussion numerous times because he absolutely stunned and then angry that she would do that, especially to someone iconic and someone had who treated her so well. She was going to return for a TNG episode, the one with Kelsey Grammar, but again she wanted a lot and they changed the shooting schedule. When they did ST VI, Meyer thought about bringing her back but then went with his first choice: Kim Cattrall. He said she'd be the best Saavik and wanted to make Saavik the traitor. Roddenberry refused saying Saavik would never betray Spock. Meyer got in a snit, claimed he had written ST II (even though he had earlier said the person who did was an idiot for saying Saavik was half-Romulan which is why he cut the scene) and that he would make his own Saavik and she'd be better than the real one. It's why Valeris has very similar scenes but is made better like saying she graduated at the top of her class and the only Vulcan who had done so (meaning Saavik hadn't). So that's why you didn't see Kirstie back and why they had a Saavik clone in STVI. The last thing they listed to Roddenberry about was not making Saavik the traitor; they refused to heed him on any other point.

Answer 3

She says she simply declined when asked to return however according to Nimoy, her agency asked for too much money so he decided to recast the role.