Marc Okrand devised the dialogue and coached the actors speaking the Klingon language heard in "Star Trek III: The Search for Spock," "Star Trek V: The Final Frontier," and "Star Trek VI: The Undiscovered Country". The Klingon language he developed has also been used in a number of episodes of Star Trek: The Next Generation and Star Trek: Deep Space Nine. In addition, he created the Vulcan dialogue for "Star Trek II: The Wrath of Khan" as well as "Star Trek III: The Search for Spock." He describes the grammar and vocabulary of the Klingon language in his book "The Klingon Dictionary" (Pocket Books, 1985; revised edition, 1992) and, along with Michael Dorn, gives an introduction to the language on the audio cassette "Conversational Klingon" (Simon & Schuster Audioworks, 1992) and shows how to make an effective use of the language on the audio cassette "Power Klingon" (co-written with Barry Levine, Simon and Schuster Audioworks, 1993).

He has also compiled a collection of Klingon proverbs in "The Klingon Way" Pocket Books, 1996).

In 1997 Marc added "Klingon for the Galactic Traveler" which studies Klingon language diversity, technical terminolgy, idioms and slang.

He has a Ph.D. in linguistics from the University of California, Berkeley, having specialized in Indian languages of the west coast, particularly those around the San Francisco Bay Area. He formally taught linguistics at the University of California, Santa Barbara, and was a post-doctoral fellow in the Anthropology Department of the Smithsonian Institute. Currently, when not involved with Star Trek, he oversees the closed captioning of various network and syndicated television programs.

In addition to "The Klingon Dictionary" and the Klingon tapes, he has written articles on both linguistics and closed captioning for several journals, collections, and programs.