One of the more interesting ways to introduce “alien” creatures into a science fiction world is to reveal that these apparent extraterrestrials are a lot more… terrestrial… than you’d think at first glance. Earth is an ancient planet, with 4.5 billion years checked off already, and that’s a tantalizing prospect for a writer. After all, who’s to say there wasn’t a civilization present for the early days of Earth, so long ago that no trace remains? There are a lot of human civilizations that have been lost to the ages as it is, so the thought of a nonhuman one disappearing isn’t exactly outlandish. From a scientific perspective, there are plenty of reasons to think there wasn’t one–no sign of resources having been extracted from the Earth prior to us, for example–but we can always fudge this for the sake of the story. That being said, here are four alien species who are a lot less alien than you might guess.

Spoiler warning–the reveal that these aliens are actually from Earth is sometimes a plot twist, so proceed with caution.

4. Voth–Star Trek Voyager

The ruler of the Voth would not be pleased about this entry.

If you’re looking for a semi-plausible source for your ancient Earthly civilizations, look no further than the dinosaurs. 65 million years ago, an asteroid strikes the earth and conveniently wipes away all evidence of the Dino Society. Problem solved! Star Trek eventually indulged in this, with Voyager‘s episode “Distant Origin,” which takes the unusual tactic of following an alien as he traces Voyager‘s route through the Delta Quadrant, believing these people might be related to his, which would lend support to the eponymous theory. Voyager has basically no idea that any of this is going on until the absolutely colossal Voth City Ship abducts their entire vessel and they’re dragged into the middle of it. Unfortunately for our Voth scientist, he’s the Galileo of dino-land, and even though his theory is correct, he’s screwed over by the people benefiting from the status quo. Guess some things never change, eh?

3. Silurians–Doctor Who

The modern Silurian makeup is pretty fantastic though, gotta say.

Of course, before the Voth, there was Doctor Who‘s answer to the dinosaur-derived civilization: the Silurians. Named after an epoch of history, the Silurians are reptilians humanoids who retreated under the surface of the Earth and basically put their entire society in stasis, waiting for the planet to recover. Individual Silurians (like Madame Vastra) and groups (such as those from the Hungry Earth/Cold Blood two-parter) have been active in the time since, and often aren’t particularly happy to find out that the surface is currently inhabited by billions of mammals. One point that the Doctor is usually very consistent on in stories involving the Silurians is that, as fond as he might be for humanity, the Silurians legitimately have a claim to the planet as well, and it wouldn’t be right for him to just kick them off their own world. Thus, most Silurian stories revolve around the idea of working out an agreement to share the Earth between humans and Silurians, sometimes successful and sometimes not. Fortunately for us, the Silurians are a fairly patient group and most of their leaders don’t seem to mind if it takes a few hundred years to get to that point. They’ve waited 65 million years already; what’s a few hundred more?

2. The X-Files

SPOILER ALERT

It’s just weird stuff.

The X-Files doesn’t really have that many different alien varieties, so even mentioning the show here might already give away the spoiler, but I left the group’s name out of the entry’s title anyway. I’ve mentioned the Black Oil before on here, as one of the biggest unanswered questions in sci-fi, but as it turns out, there is one small bit of information that I left out before–as claimed by the character known as “the Well-Manicured Man,” Black Oil was the original life form on Earth. It was definitely present on Earth prior to human civilization, as shown in the movie, but its alleged presence throughout the galaxy makes me wonder how it got off Earth in the first place. That kinda leaves things open to interpretation a bit: is the Oil just the first life form to exist here, and not necessarily native to Earth? Or was our home planet the accidental source of this galactic plague? If this is its home, then that might explain why humans aren’t as badly affected by it as some of the other aliens, or why we were able to develop a vaccine when so many others couldn’t. But would that mean that the Grays are native to Earth as well? It’s been said the Grays lived here before an Ice age forced them out. One character even theorized it came to Earth from a meteorite from Mars and helped spark life here. Hmm…

Whatever the answer, it’s clear they’re tied to the history of Earth as much as we are.

1. Fringe

SPOILER ALERT

Maybe not so much a surprise, but their humanoid appearance could always have been an illusion.

Once again, even mentioning the show kind of gives away what I’m talking about, but I’ll leave a chance, just in case. This case is a little different, in that while our “aliens” are still from Earth, they don’t predate us. Rather, the Observers are a descendant species of mankind from some possible future, possessing insanely high intelligence at the cost of reduced emotional capacity. They also have implants in the back of their necks that grant them their myriad other abilities, and appear to be the dominant species on Future Earth (and yet with all that intellect, they still screwed up the planet!). They showed up in the background of almost every episode, and even outside the show, so it was always known they were an important part of the mythology of the series. It just wasn’t apparent how important until the show was winding down.

You’d think coming from the future would negate their need to retake present-day Earth, but you’d be wrong. Since they messed up their own time so badly, they decided to come back to 2015 and take it away from us a little early, providing the setting for Fringe‘s 5th season. You know, I’m starting to see some common flaws among all these Earth-born “Alien” species…

That’s all for this week. Any alien species that are secretly Earthlings you feel are worth mentioning? Leave a message in the comments, or on Twitter @RetroPhaseShift. Working on a Primer still, so look forward to that sometime next week. If you’ve enjoyed the article, do please share it!