Star Trek VI: The Undiscovered Country's Pink Klingon Blood Explained

Some people consider "Star Trek VI: The Undiscovered Country" to be the best movie in the franchise. However, while the film has been praised for its allegorical themes, sharp script, and all-time classic villain in General Chang (Christopher Plummer), the decision to give Klingons pink blood is somewhat confusing — but there's a good reason for it.

Before "Star Trek VI: The Undiscovered Country" came to fruition, the franchise's television shows established that Klingons bleed red. That isn't the case for Chancellor Gorkon (David Warner) in this movie, however, as pink grue spills from his body following his assassination. The reason for this was to ensure the film received a PG rating, as keeping it red would probably have been viewed as too violent by censors. Clearly, Klingons having red blood isn't one of the rules everyone has to follow in the "Star Trek" universe.

That's a simple enough reason for the change, right? Well, that hasn't stopped "Star Trek" fans from proposing theories that are way more interesting than a movie chasing a PG rating.

Pink Klingon blood has returned to the franchise courtesy of "Star Trek: Discovery" and "Star Trek: Lower Decks." As such, some fans have proposed scientific reasons for the residue changing color sometimes. "Maybe it's an oxygenation thing? Like how our blood can be light or dark red depending on where it is in the body. You hit a vein or an artery and they will bleed a different color," u/StretPharmacist suggested on Reddit.

Redditor u/Willravel, meanwhile, believes certain environments can cause the blood to change color, as evidenced by the lack of oxygen on Chancellor Gorkon's ship after General Kang's forces attacked. They wrote, "Assuming there was a drop in oxygen in the atmosphere of the ship, the blood could appear lighter red or even dark pink (arterial blood, which has released its oxygen is a lighter color red than venous or oxygenated blood)." 

That said, fans such as u/Tolloworn believe that people shouldn't overthink the color of the blood, as there are no set rules for what Klingons should be. "The Klingons have been redesigned so many times the colour of the blood is the least of the issues," they observed. For now, let's just chalk up inconsistent blood colors as one of the questionable things we ignore in the "Star Trek" franchise.