Captain James T. Kirk (William Shatner) encountered many Klingons throughout Star Trek: The Original Series, but some proved to be more formidable than others. Since their debut in TOS season 1, episode 26, "Errand of Mercy," the Klingons have become one of Star Trek's most iconic alien species. Although Klingons became allies by the time of Star Trek: The Next Generation, they were one of the United Federation of Planets' most formidable foes during Captain Kirk's time on the USS Enterprise.
In Star Trek's first Klingon episode, Kirk faced off against Commander Kor (John Colicos), who proved to be a clever and unforgiving opponent. In TOS season 2's "The Trouble with Tribbles," Kirk and his crew run into Koloth (William Campbell), which results in an all-out brawl. In Star Trek's final season, Kirk goes head to head with Kang (Michael Ansara) in "Day of the Dove." Klingons also serve as villains in two Star Trek films, pitting Kirk against Kruge (Christopher Lloyd) and General Chang (Christopher Plummer).
5 Captain Koloth
Star Trek: The Original Series Season 2, Episode 13 - "The Trouble with Tribbles"
When the Starship Enterprise is summoned to a deep space station to guard a grain shipment, the crew tries to enjoy shore leave on the station alongside a crew of Klingons. Kirk is weary of being on the station with Klingons, but the Organian Peace Treaty established in "Errand of Mercy" remains in effect. Captain Koloth assures Kirk that his officers will remain peaceful. This agreement quickly falls apart when a Klingon officer insults the Enterprise and a brawl breaks out.
Captain Kirk cancels shore leave, as the Tribble initially gifted to Lt. Uhura (Nichelle Nichols) multiplies into thousands of Tribbles. As Kirk, Spock (Leonard Nimoy), and Dr. McCoy (DeForest Kelley) work to control the Tribbles, they discover a plot by an undercover Klingon named Arne Darvin (Charlie Brill) to poison the grain shipment. Meanwhile, Koloth demands a formal apology from Kirk for the way the Klingons have been treated.
Chief Engineer Scotty (James Doohan) sends the Klingons a final farewell by transporting all of the Tribbles from the Enterprise onto the Klingon vessel.
As one of Star Trek's funniest episodes, "The Trouble with Tribbles" has a much lighter tone than either "Errand of Mercy" or "Day of the Dove." Because of this, Koloth comes across as somewhat less formidable than Kor and Kang. Still, Koloth engages in the same verbal sparing with Kirk, proving he's more than capable of keeping up with the Enterprise captain. "The Trouble with Tribbles" also suggests that Kirk and Koloth had met previously, but their first encounter was never shown on screen.
4 Commander Kang
Star Trek: The Original Series Season 3, Episode 11 - "Day of the Dove"
When the USS Enterprise encounters a powerful energy being that feeds on violence, the entity pits Captain Kirk and his crew against Commander Kang and his officers. The entity manipulates the memories and emotions of both crews, fueling their anger at one another and even providing weapons for them to fight with. Kirk and Spock detect the entity and try to stop the fighting, but have little success.
As Kirk and Spock try to get to Kang, they encounter his wife, Mara (Susan Howard), and convince her of the truth. When Kirk finally reaches Kang, the Klingon Commander is initially skeptical and challenges Kirk to a duel. As the two fight one another, Kirk eventually convinces Kang to lay down his sword. The two leaders then order their officers to stand down, even laughing with one another to weaken the energy being.
"Day of the Dove" is the only episode of Star Trek: The Original Series to feature female Klingons.
Kang proves to be a clever and formidable adversary for Kirk, as he hurls insults and threats, holds his own in a fight, and even tortures Ensign Pavel Chekov (Walter Koenig). Like most Klingons during this time period, Kang hates the Federation, but he does not let that hatred completely blind him. When he realizes the truth of the situation, he makes the smart call, noting that "only a fool fights in a burning house."
3 Commander Kor
Star Trek: The Original Series Season 1, Episode 26 - "Errand of Mercy"
In Star Trek's "Errand of Mercy," the Enterprise is sent to Organia to prevent the Klingons from taking control of the strategic location. A Klingon fleet arrives at Organia soon after the Enterprise, forcing the Enterprise to retreat and leave Kirk and Spock stranded on the planet. Kirk and Spock then pose as Organians and work to sabotage the Klingon occupation. As the self-proclaimed military governor, Kor uses a mind-sifter device to probe Spock's mind, but Spock's Vulcan mental discipline allows him to fool the machine.
Even though Kirk pretends to be an Organian, Kor sees his rebellious spirit, finding an equal in him even before learning his true identity. After Kor learns Kirk's identity, he sits down to talk, expressing his admiration for Kirk and the Federation. Still, he threatens both Kirk and Spock, eventually saying: "I respect you, Captain, but this is war, a game we Klingons play to win." Kirk and Kor then go back and forth, their conversation crackling with energy as both men try to outsmart the other.
A battle between Kor and Kirk "would have been glorious,"
In the end, the Organians reveal themselves to be powerful incorporeal beings, and they put a stop to the brewing hostilities, forcing both sides to negotiate a ceasefire. Throughout this entire ordeal, Kor has Spock interrogated and imprisons Kirk, but the Organians stop the war before any actual fighting happens. As Kor laments, a battle between Kor and Kirk "would have been glorious," but it never comes to pass.
2 General Chang
Star Trek VI: The Undiscovered Country
Star Trek VI: The Undiscovered Country tells the story of how the Federation and the Klingon Empire finally achieved peace. In the wake of the destruction of the Klingon moon Praxis, the Empire seeks peace with the Federation. The Enterprise then meets with the Klingon Chancellor Gorkon (David Warner) and the two ships head toward Earth. While en route, a cloaked Klingon Bird-of-Prey fires on Gorkon's battlecruiser, and two Klingons mortally wound the Chancellor.
Because the shots appeared to come from the Enterprise, Gorkon's chief of staff, General Chang, finds Kirk and McCoy guilty assassinating the High Chancellor. Kirk and Bones are sentenced to the Rura Penthe penal colony. As later revealed, Chang himself was actually one of the conspirators behind the assassination, and he also tried to have Kirk and McCoy killed on Rura Penthe. Chang's experimental Bird-of-Prey later attacks the Enterprise after it arrives at Khitomer for the peace talks.
In the end, Spock figures out a way to home in on the cloaked ship with a photon torpedo, eventually destroying the Bird-of-Prey and killing General Chang.
After framing Kirk for murder and trying to have him killed, Chang came close to beating the Enterprise captain, but Kirk's crew stood by his side and helped him triumph. With his love of Shakespeare, Chang comes across as intelligent and cunning, but he is also willing to get his hands dirty. This, combined with Chang's intense hatred for the Federation made him one of the most dangerous Klingons Kirk ever faced.
1 Commander Kruge
Star Trek III: The Search For Spock
In Star Trek III: The Search for Spock, Commander Kruge dealt Captain Kirk his most devastating blow. After the events of Star Trek II: The Wrath of Khan, Kirk's son David Marcus (Merritt Butrick) and the Vulcan Saavik (Robin Curtis) began investigating the Genesis planet. Created when Khan Noonien Singh (Ricardo Montalban) activated the terraforming Genesis Device, the Genesis planet became increasingly unstable and soon self-destructed.
Since Spock's casket was launched at the Genesis planet at the end of Star Trek II: The Wrath of Khan, the Genesis Device resurrected Spock, but he remains without his katra (or Vulcan soul). Upon learning of the Genesis Device, Commander Kruge travels to the Genesis planet and takes David, Saavik, and Spock hostage. Meanwhile, Kirk and his crew steal the Enterprise and travel to the Genesis planet to reunite Spock's katra with his body.
Kirk kills Kruge, but he cannot get his son or his ship back.
When the Enterprise arrives, Kruge attacks and disables the ship. He then orders one of the hostages killed, and David dies protecting Saavik. Kirk then sacrifices the Enterprise to kill a Klingon boarding party and beams down to the planet to fight Kruge. In the end, Kirk kills Kruge, but he cannot get his son or his ship back. Kruge was directly responsible for David's death and indirectly responsible for the destruction of the Enterprise, making him the most formidable Klingon Star Trek: The Original Series' Captain Kirk ever faced, and the Klingon Kirk hated the most.
