Klingon was created by Marc Okrand for the Star Trek franchise.
Klingon first appeared in spoken form in Star Trek: The Motion Picture, released in 1979. Earlier Star Trek productions used only a small amount of invented Klingon speech, but Okrand expanded it into a complete constructed language for Star Trek III: The Search for Spock and later productions.
Okrand designed Klingon with grammar and sounds that would feel unfamiliar to English-speaking audiences. Its unusual features include object–verb–subject word order and a vocabulary associated with Klingon culture in the fictional universe.
The language gained a real-world community of learners, translators, writers, and performers. The Klingon Language Institute, founded in 1992, has published educational and literary material, including a Klingon translation of Hamlet. Klingon is therefore both a fictional language and a deliberately developed constructed language with active users.