John Garman Hertzler Jr. (born March 18, 1950)[4][5][6] is an American actor, author, screenwriter, and activist best known for his role on Star Trek: Deep Space Nine as the Klingon General (later Chancellor) Martok, whom he portrayed from 1995 until the series' end in 1999.

[4][8] His family lived in cities around the world including: St. Joseph, Missouri; El Paso, Texas; and Casablanca in Morocco.

On the movie screen, he portrayed Lucas in the horror film The Redeemer: Son of Satan (also known as Class Reunion Massacre), which was released in 1978.

[7] Hertzler's first involvement in Star Trek: Deep Space Nine was in the series' pilot episode "Emissary" as the Vulcan captain of the Federation starship Saratoga.

At first, Hertzler portrayed Martok as a mild-mannered Klingon, but when he was asked to make him angrier, he picked up a chair and threw it into a wall.

The chair's leg stuck briefly and he said he had also inadvertently ripped his thumbnail causing it to bleed, but it had impressed the auditors and he landed the part.

Hertzler said the writers chose Martok to be the changeling, because they thought that making the Klingon Chancellor Gowron to be an imposter was "too pat or too easy."

Credited as Garman Hertzler for the episode, he said that he got a chance to interact with some of the lead characters that Martok would not encounter, especially the ones played by Nana Visitor and René Auberjonois.

[31] Following the end of DS9, Hertzler played a Hirogen in the Star Trek: Voyager episode "Tsunkatse", which was noted for featuring pro wrestler Dwayne "The Rock" Johnson.

[31] In 2015, Hertzler joined the cast on the fan-funded short film Star Trek: Axanar as Captain Samuel Travis of the Federation.

[7][32][33][34] Outside of the Star Trek world, Hertzler appeared in the television film Pirates of Silicon Valley where he portrayed director Ridley Scott.

[26][31] Hertzler narrated the audio book entitled Barsk: The Elephants' Graveyard, written by Star Trek linguist Lawrence Schoen.

[6][42] In 2007, Hertzler moved to Ulysses, New York, and became a Resident Professional Teaching Associate (RPTA) in the Cornell University Department of Theatre, Film & Dance, where he has directed or performed in a number of productions through the 2010 season.

[52] His involvement in politics was partly because of the issue of hydraulic fracturing and concerns that the method of drilling for natural gas would destroy the Finger Lakes region.

[55] Hertzler and fellow Star Trek actor James Cromwell were among nineteen people arrested for disorderly conduct during a protest outside a Crestwood Midstream compressor station in Watkins Glen, New York, on June 6, 2016.

As part of his campaign appearances, he planned to act "in the persona of Mark Twain", to present his ideas "through the brilliant humorist for all ages".