Back in the 1960s, multi-episode television arcs weren’t a common thing. As groundbreaking as Star Trek was, they never did a story that couldn’t be wrapped up by the end of the episode. In 1987, things had changed with cliffhangers commonplace. Even then, it took until the third season for The Next Generation to do a two-part episode. Since then, it’s become commonplace as every Trek show would have a big two-part cliffhanger to end and begin a season. There would also be at least one other two-part story in the middle of the season. Some can be rather forgettable. For example, TNG’s "Descent" manages to waste the idea of the Borg growing independent and teaming with Lore. Even though it ended a great run, the Voyager finale wasn’t exactly what fans were hoping for, either.

However, other multi-parters are much better. Deep Space Nine was terrific with not just two-part tales but even three-parters or more. The latest series, Discovery, is playing on that as well. Even Enterprise could use it to good effect. While offering some amazing cliffhangers, these episodes could also show off some terrific storytelling and thrills. A few use time travel or alternate universes to raise the stakes and even bump off characters. It’s tough to choose, but the cream of the crop are obvious, not just because of the scope but the impact they made. Here are the 20 best multi-part Trek episodes ranked to show that when Trek goes beyond 45 minutes, it can be something even more magical.

20 DS9, PAST TENSE

Star Trek always does a good job with time travel stories. This two-part tale keeps that trend up nicely. While trying to beam to Earth, an accident sends the Defiant back to 2024, a time period where Earth was still in a state of anarchy. Dax is found by a businessman who leads her to the rich area of the “haves.” Sisko and Bashir are stuck with the “have nots” in San Francisco, the entire city now basically a ghetto. Sisko realizes they’re on the eve of “the Bell Riots,” a major uprising that will claim thousands of lives but pave the way for the social reforms that get Earth back on track. But in a conflict, Gabriel Bell, the man whose sacrifice will change things, is killed too early.

The effects on the timeline are instant as the Defiant suddenly becomes all that’s left of the Federation. Sisko decides the only course of action is to pose as Bell himself. He, Bashir and Dax are now on a literal race against time to ensure history turns out as it’s supposed to. It’s a more gripping storyline that gives us the sight of Sisko with a shotgun and a fun turn on how to fix history.

19 DS9, EMISSARY

Sometimes it takes a while for a show to find its footing. For example, TNG’s first season was pretty bad. So it’s impressive that right from its two-hour pilot, DS9 was already showcasing the goods to be a fine show. It kicks off in amazing fashion by showing Sisko in the Battle of Wolf 359 where he loses his wife, Jennifer. We’re soon introduced to all the major characters we’ll come to know and love, each of whom is already well defined as the cast gels perfectly from the start.

We also get the introduction of the series' main enemy, Gul Dukat, in addition to the wormhole and its mysterious aliens, plus talk of Sisko being the “Emissary” who will lead Bajor to greatness. Yes, there are some big battle scenes against the Cardassians and some exposition to set things up. But even rewatching it, the pilot nicely stands on its own to set the show’s tone,, setting the stage for one of the best sci-fi series of all time.

18 DIS, THE MIRROR UNIVERSE SAGA

It took a bit for the newest Trek series to find its groove. However, it offered a truly stunning twist with the revelation that Captain Lorca was actually from the brutal Mirror Universe. A conflict sends the Discovery there as they have to figure out a way to get back. Scene-stealer Tilly gets to pose as her own brutal counterpart as the crew plays out a scheme that involves handing Lorca over to get the materials they need to escape this reality. As usual with these storylines, the fun is seeing different versions of the characters, show up and the actors having a good time acting alongside them.

This includes discovering that this reality’s version of Voq, a foe in their own universe, is the noble leader of a resistance movement. There’s also how this universe’s version of Georgiou is the Empress of Earth. Things get worse when Lorca escapes to lead his crew in a rebellion for a big battle. Spanning five episodes, this was a great way to boost Discovery up and a fun ride through a dark Mirror Universe reality.

17 ENT, STORM FRONT

Few things make a storyline more instantly watchable than “Space Nazis.” Following a major conflict, Archer wakes up in 1944 America. It doesn’t take Archer long to realize something is wrong as proven by Nazi flags flying over the White House, Germany in command of the Eastern Seaboard and, oh yes, the sight of aliens called the Na'kuhl in SS uniforms. These aliens have managed to change the timeline to allow an Axis/Na’Kuhl alliance to conquer most of the U.S. While Archer has to survive this twisted past, the rest of the crew have to undo the damage.

This leads to the amazing sight of the Enterprise facing WWII fighters boasting high-tech weaponry. The show has fun with the idea that, as brutal as the Na’Kuhl are, they’re still not as truly evil as the Nazis. Obviously things are set right but the episodes offer a very fun twist on the usual time travel antics of Star Trek against an enemy everyone can agree needed to be fought.

16 DS9, HOMEFRONT/PARADISE LOST

This two-parter offers a rarity for Star Trek with a storyline set on Earth. When a bombing at a conference occurs, Sisko and Odo help investigate. There’s a major concern Changelings are on Earth and a feeling of paranoia is high (Sisko even suspects his own father could be a shapeshifter due to odd behavior). As more attacks occur, Sisko soon comes to a more chilling conclusion: Admiral Leyton has decided that Starfleet is too soft to handle the Dominion threat and is thus plotting a military takeover.

Much is made of how Earth, a planet long at peace, is unsure how to handle a state of war or armed police on the streets. The second part turns into a true thriller as Sisko tries to prove Leyton’s coup only to be framed as a Changeling. The fact that Leyton isn’t a bad man but truly believes what he’s doing is right makes his actions more intriguing. As one actual Changeling puts it, aliens barely have to do anything to show humans can be the greatest dangers to themselves.

15 TNG, REDEMPTION

This storyline opens with word that the Klingon High Chancellor has died and a battle for the throne is underway. The Duras Sisters are pushing for their own candidate and before long, a full-scale Klingon civil war is underway. Worf has his honor and name restored and decides to leave the ship to fight for his people. The first part ended with a stunning cliffhanger as the architect of his plot is a Romulan officer who looks just like the late Tasha Yar.

The second part has Worf fighting to get the Klingons on the same page. It turns out this woman is Sela, the daughter of a Tasha of an alternate timeline who’s a ruthless schemer. The Enterprise is soon trying to prove the Romulans are behind the war before it gets even worse. The episodes are a great showcase for Worf as he realizes that, while Klingon, he still is loyal to the Federation.

Deep Space Nine had already been a good series, but the second season finale and third season premiere was when it became a TV classic. While on a distant world, Sisko and Quark run into the Jem’Hadar, the genetically engineered foot soldiers for the Dominion. Long talked of, we finally see the Dominion as a brutal force who can easily take out starships and their mysterious “Founders” wanting control of the entire galaxy.

The third season opens with the debut of the Defiant as the crew goes to find the Founders. A complex storyline involves a look at what could happen if DS9 were to resist a Dominion-Federation alliance. Much bigger is the subplot of Odo finally finding his shapeshifting people. His joy is shattered when he discovers they’re the Founders. It’s the biggest turning point for the series and thus has to rank high on the list of multi-part tales.

13 VOY, YEAR OF HELL

With a title like that, you know this is going to be a dark ride. Voyager is defending a small ship from another race when a strange blast of temporal energy hits. It wipes one race out of existence, makes the other far more powerful and Voyager is suddenly on the defensive. It seems a Krenim scientist has developed a craft that can change history, intending to wipe out their enemies in the past so his empire grows stronger. But he fails to realize how every change just makes things worse for his species.

Voyager is soon put through months of agony, constant battles that lead to the loss of crewmembers, Tuvok blinded and Janeway pushed to the edge. The battles are huge as we see several characters perish before our eyes. In the end, of course, it’s all set to right and the timeline restored. But this showcases a true dark journey for the series -- a treat for fans.

12 DS9, IMPROBABLE CAUSE/THE DIE IS CAST

It was always a game for the DS9 crew to pretend Garak was a simple tailor. In this two-part tale, his past as an agent of the Obsidian Order comes to the fore. When his shop is bombed, Garak finds someone from his past is reaching out to him. Odo helps in the investigation to find Garak’s former mentor, Tian, wants him to join in his greatest plan: teaming the Order with the Romulan Tal Shire in an attack on the Founders’ home world. To Odo’s surprise, Garak, desperate to come back home, agrees.

The second episode has the Defiant racing to stop this before it sets off a bigger war. A dark sequence has Garak using a device to torture Odo, which neither man likes. The alliance launches their surprise attack…only they’re the ones surprised by a huge Dominion trap. It basically wipes out both forces, a move that would play into the series for a while. It also provides a fun showcase for Garak as he realizes, sometimes, you can’t go home again.

11 VOY, EQUINOX

Throughout their journey to get back to Earth, Voyager still held to the Prime Directive and other rules. Janeway was determined they would still abide by Starfleet regulations and not break their moral codes. In this two parter which bridged seasons five and six, Voyager discovers the titular vessel, another Federation ship lost in the Delta Quadrant. At first, they’re happy to join together. However, the dark truth comes out that the Equinox crew and their Captain Ransom have decided that since there’s no Starfleet, the rules don’t apply. That’s proven by how they're basically committed genocide to fuel their ship.

A big turn is that the Equinox’s holographic doctor (reprogrammed with far less morals) takes the place of his Voyager counterpart to cause mischief. Janeway’s obsession with stopping Ransom is so severe, even Chakotay questions her and how it seems wrong to go against their own. It’s a dark storyline with the Voyager crew haunted by the idea of what they could become if they let go of their moral codes.

10 TNG, UNIFICATION

This storyline got huge attention for one simple reason: Spock. Leonard Nimoy finally made the guest-appearance fans were begging for and it was great. Starfleet is concerned by news Spock has been seen on Romulus. The episode has the farewell appearance of Spock’s father, Sarek while touching on how Spock has been forging his own path. Spock is hoping to find a way to finally allow Vulcan and Romulus to join together in peaceful unification.

Sadly, the Romulans want unification on their own terms. As in, invading and conquering Vulcan. The episode has thrills but the true joy is watching Nimoy interact with Patrick Stewart and Brent Spiner. Indeed, the discussions between Spock and Data are a true highlight for Trek fans. It shows how Nimoy was always the heart of the entire franchise even in his elder years.

9 DS9, IN PURGATORY’S SHADOW/BY INFERNO’S LIGHT

This two-parter had major implications for DS9. Garak gets a message that he believes indicates his former mentor Tain is still alive. He and Worf investigate only to be captured by the Dominion. In a truly surprising twist, they find Bashir has been held captive for weeks and a Changeling has been impersonating him for the last few episodes. This fake Bashir sabotages an effort to stop a huge Dominion fleet from exiting the wormhole.

This leads into the second episode where Gul Dukat, who had just been winning fans over as anti-hero, goes back to his pure villain roots. He reveals that Cardassia has now joined the Dominion, making them stronger than ever. At the camp, Worf and the Jem’Hadar commander have a brutal fight as the rest of the team has to escape with Garak fighting a secret fear. The end sequence has the crew stopping a Dominion trap. The episodes threw a big curve for the series to rank high on the list.

8 VOY, SCORPION

For many fans, the third season finale and fourth season premiere of Voyager is when the show truly took off. It starts with a cinematic sight as two Borg cubes (each with the power to wipe out an entire Starfleet) are destroyed in seconds by a mysterious force. Voyager is soon investigating and discover that the Borg have finally met an enemy even more powerful than they are. Janeway realizes that this Species 8472 might end up ravaging the universe. She decides there’s only one course of action: Team up with the Borg.

The Borg accept the alliance and send a “liaison” in the form of Seven of Nine. Obviously, Janeway doesn’t trust the Borg to keep their word and makes her own plans to deal with them and Species 8472. It’s a thrilling episode with Voyager dealing with two threats and a nice final battle. It also paved the way for Seven to join the crew, a move that boosted the show’s popularity majorly. Yet even on its own, the episodes are great TV.

7 DS9, WAY OF THE WARRIOR

The fourth season of Deep Space Nine sparked the show up nicely. While the Dominion is a threat, the producers threw a wrinkle into things courtesy of the original Trek baddies, the Klingons. The warriors become convinced the Founders have taken over Cardassia and are ready to invade. Seeking inside knowledge, Sisko gets Worf to come to the station. However, the Klingons still invade Cardassia with Gul Dukat and the high council barely escaping.

This sets up the second half as the Klingons prepare to attack DS9. It’s a great battle sequence with fighting not just outside the station but on it. Cool moments abound such as arch-enemies Dukat and Garak fighting back-to-back against Klingons. It’s a big moment for the show with the breaking of the Federation-Klingon alliance and Worf joining the cast. Yet even on its own, it works great as a thrilling ride.

6 TNG, ALL GOOD THINGS

After seven seasons, the revival of the property went out in a very unique way. It brings the entire saga full circle as Q sends Picard on a trip bouncing through time as part of his “trial” of humanity. The future Picard is retired and living on his farm when he finds something off with his memory. He soon manages to get the old crew together on a trip that has him realizing a strange force is threatening the universe. We get a lot of old cast members returning, such as Tasha Yar and some great nods to the show’s history.

Stewart’s acting is great as the aged Picard and it’s fun seeing him and Q have a final go-around. What’s notable is how low-key this finale is. There’s no epic space battle, no huge character sacrifice and the final scene is…a card game. Yet it all works as it brings in how it was always the characters that made TNG work. While they would continue their journey in the movies, this storyline brought the original mission of the TNG crew to a beautiful close.

5 TNG, CHAIN OF COMMAND

This two-parter helped set up Deep Space Nine while showcasing how evil the Cardassians were. It starts with Picard being relieved of duty by Captain Jellico. This is part of a Starfleet plan to send Picard, Worf and Crusher on a secret mission deep inside Cardassian territory. The conflict between Jellico and Riker powers much of the storyline as it’s clear Jellico isn’t right for this command and Riker fighting not to just take the chair himself.

The second part has a captured Picard subjected to a brutal interrogation by a Cardassian operative (David Warner). It’s a tour de force performance from Patrick Stewart as Picard does his best to resist this twisted process. While the actual space conflicts are settled quickly, the psychological damage on Picard lasts longer. These episodes showcase that Trek didn’t need huge sci-fi conflicts to present some true thrills.

4 ENT, IN A MIRROR DARKLY

It seems odd that the best episodes of Enterprise don’t focus on the crew we know. It starts with a replay of the first contact between Earth and Vulcans…only for the humans to attack the Vulcans and steal their ship. We then see a much different opening credits letting us know this is the Mirror Universe. This crew is darker, more brutal and a conniving bunch ready to stab each other in the back. This Archer is on a quest to find the Defiant from an alternate universe and use it to gain his own power.

The storyline is unique and even the bold move of destroying the Enterprise in the cliffhanger. The actors are clearly having a blast playing evil versions of themselves and the entire series feels energized. It all ends with a terrific twist that shows who the real power player on this crew has been. It may not be the real Enterprise crew but this showcased the series at its creative best.

3 DS9, FAVORS THE BOLD/SACRIFICE OF ANGELS

The fifth season of DS9 ended in a bold way as the Dominion took back control of the station. Season six began with the Federation on the ropes in brutal battles while Kira and Odo tried to lead a quiet resistance on the station. This two-parter has Sisko learning the Dominion is about to lead thousands of new ships into battle. He decides it’s time to take back DS9 to stop them. The battle is as epic as it should be, some great FX work by the show and showcases some great action.

There’s also an intriguing bit of Sisko getting the “Wormhole Aliens” to take part although they warn there will be a price (which would sadly be paid later in the season). Meanwhile, Gul Dukat snaps under the pressure as he pays his own price with the loss of the only thing in the universe he loves. It’s a wild conflict that shows the stakes of war are always in the human (or alien) losses.

2 TNG, THE BEST OF BOTH WORLDS

This is when Next Generation turned into a classic series. The Borg are brought back and in a huge way. The episodes showcase the Borg on their brutal quest to assimilate worlds, painting them as an unstoppable force. The crew is aided by Commander Shelby, a woman who makes it clear she wants Riker’s job. It builds to the stunning moment where Picard is captured and then assimilated into Locutus. This leads to the greatest Trek cliffhanger of all time as Riker looks at his captain and then orders Worf to fire a weapon meant to destroy the Borg.

Fans had to wait agonizing months for the conclusion as the Borg survive. This leads to the infamous Battle of Wolf 359 where a single Borg cube annihilates 39 Federation ships. The crew is barely able to stop the Borg and bring Picard back to normal. Yet the mental scars of the experience would hang over Picard for a long time. It made the Borg the ultimate Trek villains and cemented the two-parter as a haunting story to watch, to this day.

1 DS9, THE LAST 7 EPISODES

This may seem a bit of a cheat. But the fact is that the last seven episodes of DS9 form one long massive storyline that brings the show to an incredible conclusion. It starts with a Dominion attack that devastates the Federation fleet, including the destruction of the Defiant. Both sides are rocked when Damar suddenly turns on the Dominion and leads a Cardassian revolt. This leads to Kira aiding the race that once controlled her home world. Meanwhile, Bashir discovers that Section 31 infected the Founders with a virus and races to find a cure that could stop the war. Through all this, Gul Dukat is working to unleash a demonic force that could ravage the galaxy.

The storyline packs more into seven episodes than most TV shows do in an entire season. The plots are wild such as Worf taking drastic measures to handle the Klingon leadership and spy Garak fighting for the homeworld that abandoned him. The final battle is a showcase for great special effects work. Even when the main war is handled, there’s still the final epic showdown between Sisko and Dukat. It all ends with a great montage of the crew, and the galaxy, preparing for a new future. All put together, this is the perfect capper for what some still call the best Trek show of them all, and it went out in style.