I know this may seem to be a subjective question, but it's really not. When you look at the different species in Star Trek, the UFP have predominately grey/white ships, but the Klingons and Romulans have predominately green/grey ships. Is there a reason for the use of the color green for these different species (e.g. their technology/culture etc.)?

Romulan Warbird (TNG)

Klingon BoP

Enterprise D

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    Cardassian, Kazon and Ferengi vessels are reddish-brown, Dominion vessels are pinkish-purple. Breen ships are kind of grey. In TOS both Klingon and Romulan vessels were white. – Xantec Apr 5 '14 at 1:26
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    @Xantec Breen ships look grey, but with green lighting/exhaust. And I think the Borg are actually the same, grey with green lighting/exhaust (just a lot more of it). – Izkata Apr 5 '14 at 1:29
  • @Xantec - true. It just seems that green is featured a lot as a major color in ST – Often Right Apr 5 '14 at 1:29
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    @Izkata I think in the case of the Borg it was a way to try and make them seem more "computerish", simulating the old green-screen terminals of most IBM computers in the 80's. – Xantec Apr 5 '14 at 1:32
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    Interestingly, even though the hulls are similar colors, the warp nacelles of the Klingons are red (see the Vor'cha and Negh'var ships), versus the Romulan green. Also, the Negh'var ships have red accents, like the Bird of Prey. – Xantec Apr 5 '14 at 1:36

As you can see from this link, the original Romulan Bird-of-Prey seen in TOS was actually almost the same colour as the Enterprise, though it was green-lit to give a slightly greenish hue. I was unable to find any reason as to why this was done, though it may have been simply to make the raptor decal on the underside of the ship stand out more.

Regarding Klingon vessels, there is also no reason given as to why they favour the green colour scheme. I have searched Memory Alpha, Memory Beta, Wikipedia, and several other sites that have come up in a casual Google search, and I can find no reason given for the use of the colour green. I'm tempted to say it's the designers unconsciously giving a species' ships the same colour as their blood, but we didn't find out the colour of Romulan or Klingon blood until long after their ships appeared. And the Klingon ship interiors actually moved away from their pink design before we saw Gorkon's blood.

I was confronted with a similar lack of information regarding the design philosophies for the Cardassians and Dominion. You can sometimes find reasons why the ships were designed to have a certain shape, but the colour is never really mentioned. I think the best answer we can give here is "not consciously, but Gene Roddenberry may have been locked in a room with a green clown once."


While I do not believe there is a strict canon explanation for why things are such, I have typically 'bought it' under the idea that each world, having achieved warp technology of its own accord by different methods and with entirely different sets of materials initially at their disposal, and presumably before the advent of push-button replicator technology to simply ask the computer for adamantium starships, were each simply a natural extension of their homeworld's natural and artificial resources.

In our own 21st century, space vessels are made of (among other things) titanium and aluminum - because they are both light-weight and dependable, but also because that's what we can make them out of. Aluminum is the third most abundant element found in the Earth's crust; titanium is the ninth-most. Were the availability different, perhaps we would have taken other routes altogether.

So, for Klingons and Romulans, it may well be that alloys which are green happen to be the metals they're most familiar with. They have a history of creating such ships from these metals; they know them and can work with them in a more efficient way than they would a metal from our world.

By the time the 24th century rolls around and we all know about each other, have blown each other's ships up, made friends and enemies and so on, perhaps one would expect civilizations to say, "Ah! Lousy Breen; no wonder their ships are so durable, they're made of ___ium. We should totally make our next Birds-of-Prey out of this __ium, this is going to be awesome." However, tradition can often offset adoption, in particular if your race is less focused on what the ship is actually made of and more focused on, say, interplanetary nationalism? Klingons and Romulans are pretty well-known for their reluctance to adopt off-world ideals and practices. A Klingon Bird-of-Prey built of duranium and tritanium (the Federation metals of choice, last I checked) might be seen as taboo, or at least, 'non-Klingon'.

One might expect the Romulans to know better, but then again there's always the possibility that green > grey. To that end, it may just be that whatever funny-named metals line the ships in Star Trek have their own set of trade-offs; for example, perhaps Federation ships are made of duranium because they happen to work well with our models for structural integrity fields. Meanwhile a different world with divergent but similar technology uses broccollium because their structural integrity fields work best in that setting.

  • It should be noted that real-life alloys are not typically used in starship construction. TRitanium, duranium... stuff like that would be likely. – ApproachingDarknessFish Apr 5 '14 at 22:14
  • Allegedly duranium is an alloy, but if you mean 'alloys we know of aren't used for spacecraft', steel does play a role in the build of the ISS at least. – Stick Apr 5 '14 at 22:28

I can't really state why the Klingon ships are greenish but their primary colour in most decorative settings is red. Romulans, on the other hand, well, their ships are supposed to be massive, powerful warships and they made their warships the colour of their own blood.

In this case, the colour of blood is green so they would be instinctively inclined to associate the colour green with violence just like we do with the colour red.

It's just a theory but it seems to make sense.


in the original series both klingon and romulan ships where light grey, the first instance of a green klingon ship was the first appearance of the Bird of Prey in Star Trek III, while i believe the first time we seen a green romulan ship was in TNG when the Warbird was revealed for the first time. it should also be noted that the BoP was originally built by the art department for ST III as a romulan ship, but a late script change turned the enemies in that movie from romulan to klingon but the ship model had already been built so it forever became a klingon ship.(that is why it has feather patterns on the wings)....also most of the bigger klingon ships like the TNG era Battlecruisers and Battleships tend to be a pale greenish grey rather than the darker green of the Bird of prey. as for romulans in the TNG era they are almost always green but pay close attention to the two Warbirds that come to the Enterprise's rescue against the Scimitar in Nemesis they are both of the same class but the Valdore is green and the other one is more brownish in color


I think they just like the color green. Also, green is a color that chloroplasts in plant cells make and the color helps the plant to convert light into energy that the plants can use. Maybe the Borg use green as a way to power their ships/regeneration cycle the same way plants do. Doesn't explain Klingon and Romulan ships being green, but maybe they do what the Borg do.

Note: this is entirely speculative and I do no research whatsoever

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    If you look at our tour you'll see that we like answers to be canonical, please try and refrain from using speculative answers. Maybe you could leave it as a comment instead. Speculative answers supported by research are ok. – Edlothiad Apr 16 '17 at 1:52

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