20 Things You Didn't Know About Star Trek: The Motion Picture (1979)
13. Scotty Was The Father Of The Klingon Language
A Google search for the inventor of the Klingon language will bring you to a profile of linguist Marc Okrand, who developed the Klingon language for Star Trek III: The Search For Spock (1984) and later wrote three books on the subject, including The Klingon Dictionary (1985).
But Okrand did not become involved with the Star Trek franchise until Star Trek II: The Wrath of Khan (1982). The Klingon language, which made its debut in Star Trek—The Motion Picture, was created by none other than James Doohan, the Canadian actor who played Chief Engineer Scott. (Doohan worked on the language with associate producer Jon Povill—the two men reworking ideas from UCLA professor Hartmut Scharfe that Povill says “did not sound alien enough.”)
Actor Mark Lenard, who played the Klingon Commander in the film, told journalist Preston Neal Jones about the process in 1979:
Anyway, this language was arrived at for some reason, and Jimmy Doohan, who was kind of the local resident dialectician — he claims he can do any accent — recorded it. It was recorded twice, and I hate to say it, but each time it was different. So I felt free to kind of alter it slightly anyway. I said it for Robert Wise and he seemed pleased. He just judged by how it sounded, you know.
When Okrand was hired to further develop the Klingon language for Star Trek III, he made sure the sounds matched what Doohan had created (and what Lenard had performed) for the first Star Trek movie.