However, not all plot twists hold the same weight. In the expansive universe of “Star Trek,” which spans hundreds of canonical years, some twists extend beyond altering a single episode’s events; they can resonate throughout the entire franchise, reshaping perceptions of entire series, beloved characters, or the franchise as a whole. The most effective twists catch viewers off guard, leaving them stunned when they first air. As “Star Trek” continues to evolve, with new fans exploring the series, these twists still manage to surprise even the most recent admirers.

One memorable twist occurs in “Redemption,” the finale of Season 4 of “Star Trek: The Next Generation.” This revelation prompts audiences to reconsider everything from previous narratives. It specifically ties back to the celebrated Season 3 episode “Yesterday’s Enterprise,” which itself references an earlier episode, Season 1’s “Skin of Evil.”

Sela isn’t just a familiar face; she discloses she is the offspring of the alternate Tasha Yar. Against all odds, the time-displaced Yar survived the battle, was captured, and bore a child with a Romulan officer while held captive. This stunning twist is a testament to the creativity of sci-fi storytelling and continues to astonish viewers encountering it for the first time.

“Star Trek: Deep Space Nine” broke new ground for the franchise by setting its narrative on a space station and featuring a diverse ensemble cast, including morally complex antiheroes. Among its most captivating characters is Odo, played by Rene Auberjonois. A shapeshifter discovered adrift in space by Cardassians, Odo’s origins are an enigma, even to himself. His entire existence is marked by a search for others like him, adding layers to the show’s intricate storyline.

But it’s not just the same actress: Sela reveals that she is the daughter of Tasha Yar from that alternate reality. Against all odds, the time-displaced Yar survived the battle, was taken to Romulus, and had a child with a Romulan officer while held as a prisoner of war. It’s the kind of unpredictable twist that only a sci-fi TV writer could come up with, and will stun anyone watching the series for the first time.

“Star Trek: Deep Space Nine” broke the mold for the franchise, setting its action on a space station and featuring an ensemble cast that included morally gray antiheroes. One of the show’s most intriguing characters was Odo (Rene Auberjonois), a shapeshifter who was discovered drifting in space by Cardassians and whose origins are a mystery even to him. It’s unknown to everyone who or what he is, and he’s spent his entire life wondering if there are more like him out there somewhere. 

The answer arrives in Season 2 of the series, just as the show’s grim war story breaks out and the vaunted Dominion — the greatest power in the distant Gamma Quadrant — arrives to conquer the Federation. In the two-part third season opener, “The Search,” Commander Sisko (Avery Brooks) and his crew take the USS Defiant into the Gamma Quadrant in the hopes of making contact with the Founders — the true rulers of the Dominion. At the same time, Odo begins feeling a nearly supernatural urge to travel to the Omarian Nebula — where he discovers a world full of shapeshifters like himself. But the joy of finding his people after so many years of searching is short-lived when they reveal the shocking truth: Odo’s people, known as the Changelings, are the Founders.

The Federation’s war with the Dominion isn’t the only ongoing conflict on “Star Trek: Deep Space Nine.” Also in Season 2, following a set-up in an episode of “Star Trek: The Next Generation,” we are officially introduced to the Maquis, a terrorist organization made up of former Federation citizens. Armed and ready for war, the Maquis feel betrayed by the peace treaty that ceded their colonies to the Cardassians and will do whatever it takes to protect their homes, even if it means fighting the Federation itself.

A year later, in the episode “The Search,” the series introduced a new recurring character, Lt. Michael Eddington (Kenneth Marshall), a by-the-book Starfleet officer assigned to run security operations alongside Odo when the conflict with the Dominion heats up. Loyal to a fault, Eddington is a likable, steady Starfleet officer, which is what makes it such a stunning jaw-dropper when, in the episode “For the Cause,” he phasers Major Kira (Nana Visitor) and takes control of the station in an effort to steal critical technology for the Maquis. That’s right: All this time, Eddington was an undercover Maquis agent. 

What makes it so shocking is that Eddington wasn’t just some newly introduced character. By the time his true mission was revealed, he’d appeared in more than half a dozen episodes, served faithfully on missions against the Dominion, and even helped save the lives of Sisko and his command crew on one occasion.

“Star Trek: Deep Space Nine” featured some of the most complicated characters in “Star Trek,” but even the more ordinary Starfleet officers found themselves with complex backstories, and none proved as surprising as the dark past of Dr. Julian Bashir (Alexander Siddig). Before the Season 5 episode “Doctor Bashir, I Presume,” he was a fairly simplistic character: a dedicated medical officer who worked hard to hold himself to the highest ideals of Starfleet. “Doctor Bashir, I Presume,” however, changed everything. 

The episode, which was noted for its quasi-crossover with “Star Trek: Voyager” — Robert Picardo guest-starred as Dr. Lewis Zimmerman, the man who invented the holographic doctor on that series — sees Bashir chosen to be the model for an upgraded version of the Emergency Medical Hologram. But Zimmerman’s extensive research into Bashir inadvertently exposes a secret that Bashir has been trying to hide all his life: When he was just a young boy, Bashir was diagnosed with severe cognitive impairments, and his parents had their son subjected to illegal genetic alterations that turned him into nothing short of a superhuman.

After the procedure, Bashir possessed an increased intellect equal to the smartest Vulcan and strength and stamina to match a Klingon warrior. It’s a sharp turn for the character that comes completely out of nowhere, and one that gives Bashir the kind of compelling past to rival the finest in any iteration of “Star Trek.” 

“Star Trek: Voyager” saw a Federation starship catapulted across the galaxy and forced to survive in a lawless, unexplored frontier on a quest to return home. Its crew is comprised of the usual Starfleet suspects, but also the survivors of a Maquis ship they’d been chasing, and the early portion of the series often highlighted the conflicts that arise between these two crews. The highest-ranking Maquis officer on the ship is first officer Chakotay (Robert Beltran), who is joined by his on-again/off-again lover Seska (Martha Hackett), an abrasive and embittered Bajoran woman who isn’t at all happy to be working alongside the Starfleet crew — and isn’t shy about letting her feelings be known.

Early in the show’s run, Seska appears in a number of episodes that put an emphasis on the tension between the Starfleet crew and the surviving Maquis. But in the episode “State of Flux,” we discover that Seska isn’t at all who she appears to be. Instead of a Bajoran who is fighting for the freedom of colonies along the Cardassian border, she’s actually a Cardassian spy, surgically altered to hide her true appearance. 

She’s been undercover in Chakotay’s group of Maquis for some time, and being trapped on Voyager in the Delta Quadrant ruins her plans to sabotage Maquis operations. Unlike Michael Eddington, however, Seska makes more appearances after the truth of her allegiances is discovered, returning time and time again to menace Voyager after joining their enemies, the Kazon.

Introduced in the “Star Trek: The Original Series” episode “Space Seed,” Khan Noonien Singh (Ricardo Montalban) is one of the best villains in the canon, and for good reason. Not only is he the antagonist in what is generally regarded as the best “Star Trek” film, he’s also the most nuanced and complicated baddie the franchise has ever seen. But “Star Trek II: The Wrath of Khan” wasn’t actually the last time we’d see him. In a pair of episodes across two different “Star Trek” series, Khan’s story is given new life, and he shows up in a surprise twist at the end of one of those installments.

In 2022, Season 2 of “Star Trek: Picard” introduces us to Adam Soong (Brent Spiner), an ancestor of the creator of the android Commander Data (also Spiner), from “Star Trek: The Next Generation.” This Soong, in the early portion of the 21st century, is a brilliant geneticist who is seeking to create a perfect human specimen. In the episode “Farewell,” we learn that Soong was once involved in Project Khan, a 1990s experiment that created the likes of Khan himself — meaning that Khan and Data have a connection that few ever could have imagined. 

But that wasn’t the end of the story: In a double plot twist in the “Star Trek: Strange New Worlds” episode “Tomorrow and Tomorrow and Tomorrow,” we meet a young, pre-teen Khan (Desmond Sivan) before he became a would-be tyrant — and learn that time travel by Romulan agents effectively altered the timeline, with Khan now rising to power some time in the 21st century.

The Changelings — the infamous Founders who control the Dominion in the Gamma Quadrant — were among the most feared villains in “Star Trek” history. They are ultimately defeated in the series finale of “Star Trek: Deep Space Nine,” and only after a bloody interstellar war that costs hundreds of millions of lives. But the Changelings were never seen (canonically) outside of that series, and fans wondered for years about what happened to them after their surrender to the Federation and its allies. 

They got their answer more than a quarter of a century after their last appearance, and it came in perhaps the unlikeliest of places: Season 3 of the “Next Generation” sequel series, “Star Trek: Picard.” That third season was nothing short of a “Next Generation” fan’s dream, reuniting Jean-Luc Picard (Patrick Stewart) with his old crew from the Enterprise-D as Jonathan Frakes, Marina Sirtis, Brent Spiner, LeVar Burton, Gates McFadden, and Michael Dorn all reprised their original “TNG” roles, many for the first time in decades. The villain is a twisted menace called Vadic (Amanda Plummer), and her goals are nothing less than the destruction of the Federation.

But midway through the season, we learn in a mind-blowing moment that Vadic and her foot soldiers are Changelings. It’s a left-field twist that’s all the more shocking because the Changelings were only ever seen in “Deep Space Nine,” and had never had any on-screen encounters with the “TNG” crew.

“Star Trek: Discovery” relaunched the franchise on the small screen in 2017 after more than a decade away. Its hero ship was the titular USS Discovery, a vessel with an experimental engine known as a spore drive. When activated, this bleeding-edge technology can instantly transport the Discovery anywhere in the galaxy. The third episode, “Context Is For Kings,” introduces us to the ship and its crew, including its captain: a stern, forceful officer named Gabriel Lorca (Jason Isaacs). 

Captain Lorca is a man with a shadowy past who keeps to himself, and who sometimes exhibits a darker side we don’t often see from Starfleet captains. A fan favorite, Lorca leads the Discovery into war against the Klingons, while seemingly having a hidden agenda of his own. But when we learn that agenda, it reveals a hidden truth about the character that changes the entire series.

It happens in the episode “Despite Yourself,” as the Discovery uses the spore drive, but ends up in another universe entirely. Though the crew don’t recognize it, the audience does: It’s the Mirror Universe, first seen in the classic “Star Trek: The Original Series” episode “Mirror, Mirror,” and again in several episodes of “Star Trek: Deep Space Nine.” The version of Gabriel Lorca that audiences had been following on the bridge of the USS Discovery isn’t really Gabriel Lorca — he’s Lorca’s Mirror Universe double, who’s been trapped in the main “Star Trek” timeline and trying to find his way home. 

“Star Trek: Discovery” did the unthinkable at the end of its second season, radically altering its premise by sending the USS Discovery and its crew forward in time by nearly 1,000 years. There, they discover that the Federation is in shambles and must fight to bring it back to its former glory. The third season also introduced a high-ranking Federation agent named Kovich, played by legendary film director David Cronenberg. 

For three seasons, we learn very little about who Kovich is, but he seems to have deep knowledge of time travel and even alternate parallel realities. Many fans thought he might be the head of the clandestine intelligence agency Section 31 from “Star Trek: Deep Space Nine,” while others thought he might be an immortal alien. Some even posited that he could be a future version of the holographic doctor from “Star Trek: Voyager.” But the truth, revealed in the series finale “Life, Itself,” was even more mind-blowing.

At the end of the episode, Kovich reveals his true identity: He is Daniels, the time-traveling agent seen in 2001’s “Star Trek: Enterprise.” In that series, a younger Daniels travels into the past during what he calls the Temporal Cold War, and attempts to help Enterprise captain Jonathan Archer (Scott Bakula) save the timeline from villains trying to erase the Federation from history. It’s a surprising reveal, because Daniels’ storyline was a mostly forgotten, unresolved “Enterprise” plotline, and one of the least-liked stories in all of “Trek.”

The new wave of “Star Trek” shows on Paramount+ that began with “Star Trek: Discovery” took a new turn in 2021 with the release of the franchise’s first-ever CGI-animated series, “Star Trek: Prodigy.” The series saw the return of Kate Mulgrew from “Star Trek: Voyager,” playing a hologram version of her character, Captain Janeway. Holo-Janeway, as she’s affectionately known, is part of an experimental ship, the USS Protostar, which is discovered abandoned on an alien planet by a group of misfit alien teens.

The villain of “Prodigy” is an interstellar tyrant called The Diviner (John Noble), whose daughter Gwyn (Ella Purnell) has left his side, lost her memory, and joined the ragtag crew of the Protostar. But The Diviner has a master plan that he needs Gwyn to complete, and at the end of the show’s first season, there’s a devastating plot twist that almost feels out of place in a show aimed at children. The Diviner explains that he’s actually from the future, a time when his homeworld was destroyed — and its population decimated — after making first contact with the Federation. And now he’s come back in time to stop it from happening.

It’s dark, sinister, and feels worthy of the best, most adult-centric “Trek” series. That’s a big reason why it comes as such a shock — who would have thought that this lightweight CGI-animated kids show would have such a dramatic plot twist?