Before we go into this, I want us to agree on one thing -- you have only yourself to blame!

In 2009, the movie Star Trek used the gimmick of time travel to free itself from the weight of 44 years of Star Trek history. It had become a millstone around the neck of future storytellers. But some Trekkies -- and, by "some Trekkies," I mean you -- couldn't accept that the stories and characters they loved might have been erased.

So Alex Kurtzman and Roberto Orci spitballed something to placate them -- to shut them up, really. The Prime Timeline still exists! they told us. Time travelers can't erase their own timeline, that would erase them too and create a paradox! When you mess with time, it creates another universe! Now there's another timeline running in parallel: the Kelvin Timeline.

This flew in the face of everything you'd ever seen on Star Trek. Up until Kurtzman and Orci laid their theory on us, we'd assumed time travel rewrote the history of the universe. The old history just went poof.

But this idea saved the original universe so you decided you liked it. It caught on in fandom circles. And when Bryan Fuller decided to set Star Trek: Discovery in the Prime Timeline, it became canon.

And so now I have to go and do what Trekkies have done for 50 years -- take canon super literally and apply this new information retroactively to everything that came before. Don't blame me, I'm just the messenger!

I think you can see that this whole exercise -- the absolutely ludicrous amount of thought I'm going to put into it -- the frankly absurd, and somewhat disturbing, conclusions that it's going to lead me to -- all of this...

This is all YOUR FAULT.

How Many?

Here we go...

So, now there are two Star Trek universes, right? Well, no. Because time travel happens a lot on Star Trek. Like, A LOT a lot. When you look at the whole series, you come to an obvious conclusion. There aren't just two timelines, one for the J.J. Abrams movies and one for everything else.

Then how many timelines are there?

There are FIFTEEN.

Wait, no. Let me rephrase that.

There are AT LEAST fifteen.

Because I can't even begin to figure out what the possible upper limit of concurrent Star Trek timelines is. So I'm going to stick with fifteen. Because fifteen is already a TON of universes.

And -- this should go without saying -- each one of those fifteen universes features a different version of the characters, just like the Kelvin Timeline does. Each one, like the Kelvin Timeline, is created by a time travel event.

And that time travel event doesn't end or edit the previous iteration of the universe -- no, the old timelines keeps on ticking just like the Prime Timeline does after Kelvin splits off.

And just like Star Trek (2009), Star Trek Into Darkness, and Star Trek Beyond happen in their own timeline, the other series and movies have their episodes sprinkled amongst the other fourteen timelines. It's absurd! It's a continuity nightmare!

Your fault, Trekkies. YOUR FAULT.

Does Time Travel Always Create a New Timeline?

No, thank God.

As we've said, time travel happens a LOT on Star Trek. Fortunately, just because somebody travels in time doesn't mean that they create a new continuing timeline, such as the Kelvin Timeline. There are two other possible outcomes. One is rare, the other is very common. I'll take them in that order.

1) Pre-Destination Paradox: Sometimes, it's just destiny. You travel in time, change something in the past, and that thing you changed happens to be the very thing that made you travel in time in the first place. The effect is its own cause. Happens to everybody now and then.

The best example in Star Trek is "Time's Arrow" (TNG). The crew finds Data's head in a cave, launches an investigation, and that investigation leads to Data going back in time and his head getting left in a cave. Another example is "Assignment: Earth" (TOS): Kirk's interference in the past leads to the exact outcome described in the Enterprise's record tapes.

There are other time travel episodes that may or may not be pre-destination paradoxes. I tend to think that Quark and Co.'s stint as the Roswell aliens in "Little Green Men" (DS9) was probably predestined -- that the Roswell crash was always part of Quark's timeline. We also don't know for sure whether Sisko was always predestined to replace Gabriel Bell in "Past Tense" (DS9), or whether that created a new, albeit practically identical timeline. (I'm going to avoid a headache and say it was pre-destined.)

But one thing's for sure: if you're in a pre-destination paradox, you can't create a new timeline. You're just fulfilling what's necessary for the timeline you're already in.

2) Timeline Reset: Sometimes, time travel does create a new timeline, but our heroes -- clever time travelers that they are! -- manage to "hit the reset button." Basically, they manipulate time to invalidate whatever created the new timeline, and it collapses. In these stories, a new timeline exists briefly but it doesn't become an ongoing timeline.

One of the best examples is the earliest example: "Tomorrow Is Yesterday" (TOS). Kirk accidentally creates a new timeline by kidnapping an Air Force pilot, father of a future space explorer, but he manages to return the pilot with no memory of what happened, so the new timeline collapses and the Enterprise can return to its old timeline.

Other prominent examples -- and there are too many to list them all here -- are "The City on the Edge of Forever" (TOS), "Tapestry" (TNG), "Children of Time" (DS9), "The Year of Hell" (VGR), and "Storm Front" (ENT).

The forgettable episode "Time and Again" (VGR) has the distinction of being both a pre-destination paradox and a timeline reset. True to its humanist roots, Star Trek tells us that free will exists, even -- impossibly -- inside a pre-destination paradox. But please don't spend any time thinking about THAT, or you'll never follow what comes next.

Creating a Timeline

If a Pre-Destination Paradox and a Timeline Reset won't create a new ongoing timeline, what will?

There are two things necessary:

1) You must travel BACK in time. As opposed to forward. The future is always in motion. The past is written in stone. In other words: Everything you do alters the future, so you can't create a new timeline by going there.

However, if having seen the future, you travel BACK in time to your own present to change something, then you can create a new ongoing timeline. Ditto if you receive a message from the future. The important thing something traveled backward, even if it's only information.

2) Having traveled back, you must change something. And that change must have an effect that reaches into the future.

How big does that change need to be? Are we talking a major change, like killing Hitler? Or is this more like Ray Bradbury's butterfly effect where simply stepping on a bug will create an alternate timeline?

I have no idea. For the sake of argument, let's say it has be a BIG change -- like Nero destroying the Kelvin. Because if a tiny change is enough, there could be millions of Star Trek timelines, not just fifteen.

Meet Your Timelines!

So, what are these fifteen timelines? Let's get to know them all better.

Let's start with the original timeline. The Prime Timeline, right?

Sorry, no. I know this is confusing, but the Prime Timeline from Star Trek (2009) isn't even close to being the original Star Trek universe. If you follow the Kurtzman/Orci/Fuller theory of time travel to its logical conclusion, that is.

I'm going to call the first timeline the Classic Timeline. The Classic Timeline began at the Big Bang and chugged along, minding its own business, for around 13.9 billion years (as far as we know), unchanged by pesky time travelers. The Classic Timeline is where all of Star Trek: The Original Series happened. All of The Animated Series too (if you like that sort of thing). The Motion Picture happened there. So did Wrath of Khan and Search for Spock.

And then Captain Kirk decided that he just had to save the whales.

So he travels in time to 1986 and saves two whales. Along the way, he abducts a marine biologist, sends a Russian to invade a US aircraft carrier, and makes sure transparent aluminum gets invented early. All of this creates a new timeline: the George & Gracie Timeline.

Now, the whales and the aluminum and the aircraft carrier and the marine biologist don't add up to much at first, so the George & Gracie Timeline is probably quite similar to the Classic Timeline until 2286 -- that's the year when Kirk travels back to the future and uses his new whales to save the Earth from an alien Probe. From that point on, the G&G Timeline gets very different from the Classic Timeline.

Say, whatever happened to the Classic Timeline? Did it get rewritten, replaced with G&G? We always thought so, but Kutzman, Orci and Fuller tell us NO -- it still exists.

That's right, the timeline continues on from the point where Kirk and crew went back in time. And they never come back with the whales, because they've created the G&G timeline in the past so that's the future they return to. And the Probe destroys Earth and everyone dies and the Federation probably picks up the pieces and goes on from there.

Think about that: in the timeline where all of Star Trek up to this point has happened, the Earth is destroyed. Sarek, Chapel, Rand? All dead in the Classic Timeline. But we don't care because Star Trek is happening in the G&G Timeline now.

At least, for a while...

The Other Timelines

Just to make sure we all understand something: The Classic Timeline and the G&G Timeline are not totally separate. They're one timeline up until 1986 -- then they branch. Before 1986, you're in both of them. After, you're in just one or the other. They diverge in 1986.

And just like the Classic Timeline in 1985 is actually both Classic and G&G, the G&G timeline in, say 2300, is also all the other timelines that diverge from it in the future. I mention that because it becomes important later. All that's clear, right?

Right. Moving on.

Star Trek V, Star Trek VI, and the opening of Star Trek Generations happen in the G&G Timeline. With this caveat: Kirk, Spock, McCoy, Scotty, Uhura, Sulu and Chekov are all the Classic Timeline versions. They're like Spock Prime wandering around the Kelvin Timeline. Spock Classic, Kirk Classic. They can never get home. For some reason this doesn't bother them.

By the way, what happened to the Kirk and crew who were born in the G&G Timeline? Well, they were also confronted with the destruction of Earth by the Probe, and not knowing that their duplicates from the Classic Timeline were already on their way with whales, the G&G Kirk also attempted time travel. Best case scenario, he's in a different timeline now. Worst case, he time-warped into a temporal paradox caused by Kirk Classic and was erased from history. Heavy.

Anyway, after the Enterprise-B gets launched in Generations, the Lost Era starts, and in the year 2344 the Enterprise-C goes to save a Klingon outpost from Romulans and ends up falling into a temporal rift.

It travels forward in time. Now, traveling forward, you'll recall, can't create a new timeline. When the Enterprise-C gets to 2366 and sees a future where the Federation is about to lose a long, bloody war with the Klingons, that isn't some kind of alternate timeline.

That's right: "Yesterday's Enterprise" (TNG) isn't an alternate history. It's the conclusion of the George & Gracie Timeline that began in The Voyage Home.

And when I say "conclusion," I mean the last we'll see of it -- because when the Enterprise-C returns to the past and creates a new timeline, the G&G Timeline isn't erased any more than the Classic Timeline was. Sure, the Enteprise-D was destroyed there, Picard and his whole crew is dead, and the Federation probably gets conquered by the Klingons. But why should we care? We're on to the next timeline!

I'm going to call the timeline that the Enterprise-C creates by impressing the Klingons with its crew's bravery by the name Next Gen A. Why "A"? We'll see in a minute.

You're probably getting the hang of this by now, so I'm going to blow through these timelines a little faster. You surely understand that Next Gen A diverges from the G&G Timeline in 2344 and an alternate version of everyone alive then is created; but, like Kirk and crew the last time around, there are some refugees from the G&G Timeline that enter Next Gen A -- namely, the G&G Tasha Yar and the other Enterprise-C survivors. Fat lot of good it does them. They're all killed by Romulans within a few years.

Next Gen A includes the first season of Next Generation and most of the second. In "Time Squared" (TNG), we learn that the Enterprise-D from Next Gen A, which the series has followed up to this point, was destroyed in a time anomaly, but that Picard A managed to travel back in time and create the Next Gen B Timeline. Here the Enterprise escapes from the anomaly -- but not before Picard B kills Picard A. The Next Gen A timeline continues on without its Enterprise. We never see that timeline again.

And we move on with an entirely new group of alternate characters. NO ONE from any of the previous universes makes it into the new timeline. Oh well.

A ton of episodes happen in the Next Gen B Timeline. The rest of Star Trek TNG happens there, as do most of the first three years of Deep Space Nine, the first season of Voyager, and the 24th century parts of Star Trek Generations. We leave this timeline in "Visionary" (DS9) right after Miles O'Brien dies of radiation poisoning and Deep Space 9 is blown up by Romulans.

Fortunately, the station crew manages to get a new timeline off the ground in the nick of time -- the Deep Space A Timeline. Like Next Gen B, no survivors -- although it's interesting that the Miles O'Brien in Deep Space A is actually a refugee from a different timeline that collapsed. Weird.

We don't stick with Deep Space A for long. After Captain Sisko gets himself sucked into subspace, we see Deep Space A's future history on fast-forward in "The Visitor" (DS9). The Klingons take over the station and keep the Dominion bottled up in the Gamma Quadrant. Which actually seems way better than the billions of senseless deaths in the Dominion War. Way to go, Klingons!

But Jake Sisko needs his dad, so Ben Sisko averts the accident that stranded him in subspace, and Star Trek moves to a new timeline, Deep Space B (although we take Sisko A with us).

Something really weird happens to the Deep Space B Timeline, something totally unique in this long twisted saga. It technically ends after less than a year in "Accession" (DS9), when the Prophets send would-be Emissary Akorem Laan back home to the 22nd century. This creates a new branch straight from the George & Gracie Timeline where Akorem's career as a poet has a second chapter. But not wanting to mess things up too much, the Prophets merge the new Akorem Timeline with Deep Space B, to created a joint Akorem/Deep Space B timeline where people can remember both versions of the past. Kira shrugs this off, but it's actually pretty disturbing!

But, hey, good for the Prophets -- that's what I say! Living outside of linear time can't be easy. If you've read this far and are actually managing to keep all these timelines straight, you're getting a tiny glimpse of what it must be like to be a Prophet.

Moving on!

The DS9 crew moves on to the Deep Space C Timeline pretty quickly in "Trials and Tribble-ations" (DS9), where we see what "The Trouble With Tribbles" (TOS) looks like in the Akorem Timeline -- which I'm sure you remember is a branch of the George & Gracie Timeline, which, in turn, runs parallel to the Classic Timeline, which is where the first version of "The Trouble With Tribbles" happened.

Deep Space C is exactly the same as Deep Space B, except Tribbles are rescued from extinction. So it's 100 percent better.

And it's only a few months before the Borg attack, and Picard follows them into the past, and the First Contact Timeline takes over. In Deep Space C, the Borg are defeated, but Deep Space 9 must do without Worf because Worf C, Picard C and the rest of the Enterprise-E crew have moved to the First Contact Timeline.

Like Akorem, the First Contact Timeline diverges straight from the George & Gracie Timeline in 2063 before almost all of this other nonsense happened. So it contains a new (though largely similar) version of basically the entire Star Trek story, with alternate versions of all the characters. But there are only a few changes from G&G: the Phoenix ground crew and some Montana drunks got killed by the Borg, and Zefram Cochrane and Lily Sloan now have a lot of fore-knowledge. Also, there are some dormant Borg in the Arctic who are gonna make a bit of trouble.

Most of the next two seasons of DS9 and Voyager happen in the First Contact Timeline. In 2375 Chakotay and Harry Kim make it home from the Delta Quadrant aboard the Delta Flyer but Voyager is destroyed. In 2390 they decide they can't live with it and send a message into the past, creating the Voyager A Timeline, which diverges from First Contact in 2375. Chakotay and Kim of First Contact die in the effort and still don't manage to bring back their Voyager.

But, once again, we don't care, because we watch the rest of Voyager after "Timeless" (VOY) in the Voyager A Timeline, where our intrepid heroes take 20 more years to get home. Not good enough for Admiral Janeway! She travels from 2404 in Voyager A back to 2377 to create Voyager B, defeats the Borg Collective of that time, and get the ship home right away.

Now we go far into the future of Voyager B, where a number of factions are plotting to change history. Future Guy (probably not his real name) is in the 28th century. Vosk and the Na'kuhl are in the 29th century. Daniels, a squirrelly Federation time agent, is in the 31st century. There are others too, we're led to believe.

All of these people either travel back in time or recruit agents in the past. Through their collective hapless mucking about, they establish a Temporal Cold War Timeline. It diverges from the First Contact Timeline around 2151.

The first two seasons of Star Trek: Enterprise happen in this timeline. To be clear, there's probably a Jonathan Archer and an Enterprise NX-01 in the Classic Timeline, and the George & Gracie Timeline, and the First Contact Timeline. But they aren't the ones we got to watch.

Since Star Trek: Nemesis came out while the first two seasons of Enterprise were airing, I think there's a good case to be made that Nemesis takes place in the 24th century of Temporal Cold War Timeline. Which, when you think about it, is a huge comfort! It isn't even in the same branch of timelines as the other 24th century stuff. It's got nothing to do with TNG at all!

A few hundred years after Nemesis, in the 26th century, and still in the Temporal Cold War Timeline, the galaxy is invaded by trans-dimensional baddies called Sphere Builders. The Federation stops them at the Battle of Procyon V, so they go back -- WAY back -- to the 12th century AD, when all the timelines were still the Classic Timeline. And, while the Temporal Cold War Timeline goes on to some unknown conclusion, the Sphere Builders create the Xindi Timeline. They spend about a thousand years creating the Delphic Expanse, then in the 22nd century they manipulate the Xindi into destroying Earth. Earth sends the NX-01 to stop them, but Earth gets destroyed anyway, the Federation is never founded, and the human race is wiped out after settling on Ceti Alpha V.

Just before Ceti Alpha V goes boom, Archer and T'Pol of the Xindi Timeline manage to create a new timeline of their own. This doesn't stop the fact that the Xindi kill them, annihilate humans, and then the Sphere Builders probably take over the galaxy in the Xindi Timeline. No, the Xindi Timeline is definitely the worst if you're one of the good guys. But we don't have to watch any of that happen, because the show moves into another timeline.

And this timeline -- at last! -- at long, long last! -- is the Prime Timeline from Star Trek (2009).

How can I be sure? Because Captain Bathazar Edison from Star Trek Beyond grew up in the Prime Timeline (before it diverged from Kelvin), and he fought in the Xindi War. The only timeline where that war happened, and we won it, is the one created by Archer and T'Pol at the end of "Twilight" (ENT). So that was the Prime Timeline.

While the Prime Timeline is not the same at the Classic Timeline or the various Next Gen Timelines, it does have a lot in common with them. All of the episodes of Enterprise after "Twilight" happen in the Prime Timeline. Star Trek: Discovery does too. We know that something similar to the TOS movies took place because in Star Trek Beyond we saw Ambassador Spock's photo of the TOS crew from the movie era. We also know that something similar to The Next Generation happened, because the Riker-Troi scenes in "These Are the Voyages" (ENT) take place in the Prime Timeline.

Judging from Riker and Troi's appearance, "The Pegasus" (TNG) must've happened a decade later in the Prime Timeline than it did in the Next Gen B Timeline. Just sayin'.

Finally, the future scenes of Star Trek (2009) happen in the Prime Timeline. Romulus was destroyed there by a super nova in 2387, causing Nero to time travel to 2233, where he destroyed the USS Kelvin and created the Kelvin Timelinea.

So There You Have It...

Those are the 15 Timelines in which Star Trek episodes and movies happen.

You have the Classic Timeline, which diverges into the Xindi Timeline (12th century), and the George & Gracie Timeline (1986).

The Xindi Timeline splits into the Prime Timeline (2153) and then the Kelvin Timeline (2233).

Meanwhile, the George & Gracie Timeline splits into the First Contact Timeline (2063), the Akorem Timeline (22nd century), and the Next Gen A Timeline (2344).

Next Gen A leads to a succession of new timelines: Next Gen B (2365), Deep Space A (2371), Deep Space B (2372), and Akorem/Deep Space B (2372).

The Akorem Timeline diverges into Deep Space C (2267).

The First Contact Timeline splits into the Temporal Cold War Timeline (2151), Voyager A (2375), and the Voyager B (2377).

To Sum It All Up


Congratulations! You made it to the end!


Almost. A ton of this is debateable, so I want to show my work. Here is a list of which episodes occur in which timelines.
















And here's a list of time travel episodes, divided by type: