Star Trek: The Original Series actor John Colicos nearly didn’t return to Star Trek: Deep Space Nine, but he thankfully changed his mind, leading to future appearances by the legendary Klingon, Kor. John Colicos holds the distinction of being the actor who originated the Klingons in Star Trek, appearing as the main antagonist in TOS season 1, episode 27, “Errand of Mercy”. Kor made such an impression on the TOS cast and crew that Gene Roddenberry wanted to make him a recurring character. Unfortunately, scheduling commitments meant that Colicos was unable to reprise the role of Kor for “The Trouble with Tribbles” and “Day of the Dove”.
With John Colicos unavailable for future Star Trek: The Original Series episodes, the characters of Koloth (William Campbell) and Kang (Michael Ansara) were created for “The Trouble with Tribbles” and “Day of the Dove”, respectively. Star Trek: Deep Space Nine season 2, episode 19, “Blood Oath” brought back all three TOS Klingons, teaming them with Lt. Jadzia Dax (Terry Farrell). “Blood Oath” is a highly regarded episode of DS9 season 2, but it could have been very different if John Colicos had decided not to return as Klingon Dahar Master, Kor.
When John Colicos received the script for “Blood Oath”, he completely disagreed with the handling of the character of Kor. In the original script, Peter Allan Fields wrote Kor as a Klingon version of William Shakespeare’s Falstaff character. A boastful knight and something of a drunk, Falstaff is largely a comic character in the three Shakespeare plays in which he appears. John Colicos objected to a similarly comic and bufoonish take on Kor, telling Star Trek: Deep Space Nine – The Official Poster Magazine issue 8 that he told DS9 producer Michael Piller:
Michael Piller assuaged John Colicos’ fears somewhat by telling him that Kor would become a hero by the end of “Blood Oath”. The deal was finally sealed when it was decided that, out of the three TOS Klingons in DS9, Kor would survive his Star Trek: Deep Space Nine appearance, living to tell the tales of Kang and Koloth’s heroic deaths. Indeed, John Colicos was adamant that Kor should not die in “Blood Oath”, telling Star Trek Monthly issue 55 that:
Due to the prosthetic changes between Star Trek: The Original Series and Star Trek: Deep Space Nine, it’s not immediately apparent that it’s the same Kor, Kang, and Koloth in “Blood Oath”. However, it becomes clear very quickly that this is a historic classic Klingon reunion on DS9, which is a big deal. A TOS Klingon reunion without John Colicos, the actor who originated the Klingons on Star Trek, would have felt incomplete.
If John Colicos had turned down the chance to return as Kor from Star Trek: The Original Series, then Peter Allan Fields would have to have created a new Klingon to join Kang and Koloth’s quest. The story would still have made for a classic Klingon episode, but any Kor replacement would have felt like an impostor. It’s lucky then that John Colicos was persuaded to reprise the role of Kor in Star Trek: Deep Space Nine, where he clocked up two more appearances after “Blood Oath”.
All episodes of Star Trek: The Original Series and Star Trek: Deep Space Nine are available to stream on Paramount+.