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The Best On-Screen Star Trek Crossovers Ranked

Since the 1980s, the long running "Star Trek" franchise has seen multiple generations, starships, and different crews explore the final frontier. From the original 1960s "Star Trek," to "The Next Generation," "Deep Space Nine," and "Voyager" from the '90s, to the more recent editions like "Discovery," "Lower Decks" and "Strange New Worlds," different eras speak to different groups of fans. 

All the various spinoff shows and movies released over the course of 50 years have created many opportunities for characters from different "Star Trek" installments to meet on-screen. In the days before the MCU, "Star Trek" was one of the first deeply interconnected media franchises with on-screen crossovers reinforcing the connectivity of its universe. From cameos to bona fide crossover events, "Star Trek" has seen plenty of epic team-ups with characters from different shows and movies getting together in new adventures.

From a meeting of captains and a trip into the past to the resurrection of long-dead heroes, this is a list of the best on-screen crossovers ever seen in "Star Trek."

14. Emissary (Deep Space Nine)

"Emissary" is the pilot episode of "Deep Space Nine" in which the Enterprise from "The Next Generation" docks at the former Cardassian station to open the series. "DS9" features onetime "TNG" recurring character Chief Miles O'Brien (Colm Meaney), and this appearance from his former crewmates from the Enterprise helped ease fans into the idea of exploring a strange new series.  

Though the crossover elements in this entry are relatively minor — hence its low spot on this list — it does feature the franchise's only meeting between Captain Picard (Patrick Stewart) and Commander Sisko (Avery Brooks), the two leads of their respective series. Their lone scene together makes it immediately clear that Brooks' Sisko does not operate anything like Picard. In a tense exchange that demonstrates the differences between the two officers, the emotionally charged Sisko tests the calm and collected Picard with the notion that he may be considering leaving Starfleet altogether.

But in the rawest moment between the two, Sisko reminds the Enterprise's captain that they've actually met before ... in battle. Some years earlier, Sisko was aboard a ship that confronted the Borg at Wolf 359 when Picard was the villain called Locutus of Borg in the "TNG" two-parter "The Best of Both Worlds." Unfortunately, "Emissary" is just one of two episodes in which members of "TNG" and "DS9" meet while both shows were on the air.

13. Projections (Voyager)

A crossover with "The Next Generation," the "Star Trek: Voyager" Season 2 episode "Projections" guest stars "TNG" recurring character Reginald Barclay (Dwight Schultz) despite the series being set on opposite sides of the galaxy. A mind-bending mystery, it centers on The Doctor (Robert Picardo) who is activated in sickbay to find the ship deserted after an attack from the Kazon. But just as the episode appears to be turning into an action-thriller, The Doctor gets a visit from Barclay, who tells him that he's not really on Voyager and isn't a holographic doctor at all. Instead, his name is Lewis Zimmerman — a Starfleet researcher on Earth.

Insisting The Doctor is really human, Barclay claims that Voyager is actually a holodeck simulation to test the effects of long-term deep space assignments. But thanks to a radiation surge, something went wrong, and now Zimmerman is trapped in the simulation and suffering delusions from radiation poisoning. The only way out, according to Barclay, is to destroy the ship, ending the program. Now The Doctor must decide what is real; if he chooses wrong, his program — or his life — could be lost.

Thanks to a clever plot to get a "TNG" cast member aboard "Voyager," viewers were treated to another appearance by fan-favorite Schultz back in the role of Barclay. His chemistry with Picardo certainly helped convince "Voyager" producers to bring him back later in the series.

12. Birthright (The Next Generation)

In 1993, "Star Trek" had two different series airing alongside each other for the first time in the franchise's long history with the launch of "Deep Space Nine." But after the "DS9" opener, the two crews would only participate in one more full-blown crossover during the two years they would both share the airwaves in a "Next Generation" episode titled "Birthright." Unfortunately, the crossover aspect really only applies to the first half of the two-parter. 

The Enterprise arrives at DS9 for some diplomatic talks on Bajor. We get a humorous scene with Geordi (LeVar Burton) aboard the station sampling some of the food at the replimat while Picard and Dr. Crusher (Gates McFadden) enjoy the promenade. The meat of the episode involves Data (Brent Spiner) working with Bashir (Alexander Siddig) aboard the Enterprise when the android officer discovers an apparent glitch in his systems that results in hallucinations.

Secondarily, in the subplot that becomes the basis of the second part of the story, Worf (Michael Dorn) is approached by a Yridian who tells him that his father Mogh may still be alive, held prisoner by Romulans on a far-off world. A strong episode with a pair of intriguing stories, it shows Worf is right at home on DS9 where he winds up full time just a couple of years later. 

11. Defiant (Deep Space Nine)

Following the end of "Star Trek: The Next Generation," the crew of the Enterprise headed to the big screen, but that didn't mean the crossovers with sister series "Deep Space Nine" and "Voyager" had to end. In the third season "DS9" episode "Defiant," the show is paid a visit by an individual who appears to be Commander Riker, who stops off at the station while apparently on shore leave. Riker hits it off with Major Kira (Nana Visitor) and asks to see their new little warship, the USS Defiant.

But instead of touring the ship, Riker kidnaps Kira and steals the starship, revealing that he's actually Thomas Riker, the genetic clone of the Enterprise's first officer created in the "TNG" episode "Second Chances." Now a member of the Maquis, he plans to use the Defiant to expose a secret fleet of Cardassian ships he claims are assembling in a nearby nebula. With the Maquis now in possession of the most powerful ship in the sector, Sisko must team up with Dukat (Marc Alaimo) to try and stop him.

With guest star Jonathan Frakes returning in an unexpected reprisal of a nearly forgotten character, "Defiant" is more than just a "TNG" crossover. It's also a gripping adventure that explores the tense relationship between the Federation and the Cardassians, as well as between Sisko and Dukat.

10. Pathfinder (Voyager)

Dwight Schultz made five appearances on "The Next Generation" as Reginald Barclay but, believe it or not, he made more on "Star Trek: Voyager." And it's not just Schultz who makes the "Voyager" sixth season episode "Pathfinder" a crossover — it's the return of Marina Sirtis as Counselor Deanna Troi. It's also Barclay's first official visit to the series after he's revealed as a computer hallucination in "Projections."

A researcher working on a project to locate Voyager in the Delta Quadrant, Barclay meets with Troi to discuss the serious issues he's faced with his superiors. It seems that Barclay has become obsessed with Voyager, living inside a holodeck recreation of the ship and ultimately gets removed from the project due to his instability. Believing that only he holds the key to finding and communicating with Voyager, Barclay takes matters into his own hands and breaks into Starfleet's research lab to take control of the project.

An unconventional episode centered entirely on Barclay and Troi, the crew of Voyager only appear at the tail end of the episode when they finally make contact with Starfleet Command in one of the most emotional moments of the series. As for Marina Sirtis, she would reprise her role as Troi in two more episodes of "Voyager," including "Lifeline," which narrowly missed making this list.

9. Star Trek (2009)

In 2009, J.J. Abrams relaunched the "Star Trek" franchise with the efficiently titled film "Star Trek," featuring an all-new cast aboard the Enterprise. But to the surprise of many, the film includes the return of one of the most beloved characters from "Star Trek: The Original Series" — Spock, played by Leonard Nimoy.

In the film, Spock inadvertently creatures a rift in space and an alternate reality by failing to save the Romulans' doomed home world. While he's pursued by a vengeful Romulan called Nero, Spock is thrown into this alternate universe more than 100 years in the past, where he meets a younger version of James T. Kirk (Chris Pine) and recruits him to help stop the villainous madman by assembling the crew of his original Enterprise in this new reality.

Nimoy's unexpected return as Spock was celebrated by fans and provided the movie's only link to the old universe of "Star Trek" stories. He reprised the role in a cameo in the film's sequel, "Into Darkness," marking the only crossover to date between the "Prime Timeline" and the "Kelvin Timeline" of stories. But beyond the excitement of seeing Nimoy put the pointed ears on one more time, the film was a big hit with moviegoers and critics alike and panned out as one of the best blockbuster movies of the 2000s, kicking off a new series of cinematic "Star Trek."

8. Blood Oath (Deep Space Nine)

Few crossovers are as amusing as the "Deep Space Nine" episode "Blood Oath." The story sees the unlikely return of three characters from the original "Star Trek" series more than 30 years later. This trio of Klingons includes Kor (John Colicos) from "Errand of Mercy," Kang (Michael Ansara) from "Day of the Dove," and Koloth (William Campbell) as Koloth, who spars with Kirk in "The Trouble with Tribbles."

In "Blood Oath" we learn that all three share more than just a history with the original Enterprise; they are all good friends with a deep bond. Years earlier, a notorious criminal called the Albino (Bill Bolender) murdered each of the Klingons' firstborn sons, and they swore an oath to hunt him down and make him pay. But one other individual took the oath with them — Ambassador to Qo'noS Curzon Dax, former host of Jadzia Dax (Terry Farrell). Feeling bound by duty to aid in their quest, Jadzia joins the three Klingons in a mission to kill the Albino now that Kang has finally learned of his whereabouts.

In a story of brotherhood, loyalty, and revenge, the three returning actors slipped neatly back into their roles and made "Blood Oath" an early "DS9" classic. Colicos even returned a few more times, making Kor a recurring character on the series.

7. Death Wish (Voyager)

Set in the far-flung Delta Quadrant, "Star Trek: Voyager" required serious sci-fi shenanigans to cross over with any of the other series in the franchise, but it managed to do so quite a few times during its seven-season run. One of its most important crossovers comes in the form of the Season 2 entry "Death Wish," which includes appearances by the immortal trickster and foil of Captain Picard, Q (John de Lancie), as well as a cameo from Jonathan Frakes as Commander Riker.

While on their journey back to Earth, Voyager comes across a comet that turns out to be a prison for a member of the Q Continuum. After he's inadvertently released from confinement, it's discovered that this new Q — dubbed Quinn (Gerrit Graham) — was sentenced to eternal imprisonment for attempting to end his own life. Once Quinn is freed, Voyager is visited by Q from "The Next Generation," who wants to put Quinn back in his cell. When Quinn asks for asylum, Q agrees to a hearing, and one of the witnesses he calls is none other than the Enterprise's first officer, William T. Riker.

Like Kor, Q would become a recurring presence on "Voyager," with "Death Wish" the first part of a storyline that explores the nature of the Q Continuum. Though the episode examined deep, thought-provoking issues, there's no denying that its inclusion of "TNG" favorites Q and Riker help make it a standout.

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6. Star Trek: Generations (1994)

Without a doubt, the biggest "Star Trek" on-screen crossover has to be the 1994 film "Star Trek: Generations," which sees the two Enterprise captains meeting for the first time. After the conclusion of "The Next Generation" television series, the time had arrived for the crew to jump to the big screen. To mark the occasion, the studio did what many might have thought impossible — getting William Shatner back to star alongside Patrick Stewart's Captain Picard for an epic adventure that literally passes the torch of "Star Trek" movies to the next generation.

In the first part of the film, set during Kirk's era, the original Enterprise captain is seemingly swept up by a dangerous spatial distortion called the Nexus and seemingly killed. Decades later, a villainous madman called Soran (Malcolm McDowell) believes the Nexus to be the key to immortality and sets out to destroy entire planets in order to draw it to him. But with the Nexus' incredible power, Picard manages to resurrect the long-lost James T. Kirk. Together, they save millions of lives and stop Soran once and for all.

Though it wouldn't be the most fondly remembered among the "Star Trek" movies, there's no denying that bringing together two generations of "Trek" makes it a major milestone. 

5. Flashback (Voyager)

Original "Star Trek" star George Takei took his character Sulu to the captain's chair of the USS Excelsior in "Star Trek VI: The Undiscovered Country," a movie that includes a memorable opening sequence in which his ship is rocked by the destruction of a Klingon moon. Though we never get to see the further adventures of the Excelsior, Takei got a chance to return to Sulu in a landmark episode of "Star Trek: Voyager" produced to coincide with the franchise's 30th anniversary.

In "Flashback," a terrible mind-altering disease infects Vulcan security chief Tuvok (Tim Russ). For a cure, he must mind meld with Captain Janeway (Kate Mulgrew) to explore his memories. Janeway and Tuvok must re-examine the events in Tuvok's past and identify the origins of his illness if they are to find a cure. In these memories, we learn that Tuvok was a young ensign aboard the USS Excelsior under Captain Sulu when Kirk and the Enterprise were caught up in a plot to assassinate the Klingon chancellor. 

Recreating the events of "Star Trek: The Undiscovered Country" with a new twist, Takei hops back into the guise of Captain Sulu with style and seeming ease to the delight of "Trek" fans everywhere. In fact, some — including actress Grace Lee Whitney who played Janice Rand in the episode — claimed that "Flashback" was intended as a backdoor pilot for a Sulu series. Sadly, such a spinoff never materialized.

4. Sarek (The Next Generation)

While the two-hour pilot episode of "Star Trek: The Next Generation" features a brief cameo from "Original Series" star DeForest Kelley as Leonard McCoy, the 1987 series eschewed crossovers with its iconic parent series for its first few years. But by Season 3, the series felt comfortable making some connections, beginning with its first major guest appearance from a character originating in the classic "Star Trek" in the aptly titled episode "Sarek."

The father of Spock, Sarek (Mark Lenard) appears in the classic episode "Journey to Babel" as well as in four of the feature films. Here, Picard's Enterprise is instructed to escort the aging Ambassador Sarek on the final mission of his illustrious career — negotiating a peace treaty with the enigmatic Legarans. But when he comes aboard, the crew begins exhibiting strange behavior that is traced back to the ambassador, who we learn has been suffering a rare and incurable Vulcan disease. While Sarek denies his condition, Picard must find a way to convince Sarek to do what's best for his mission, even if it means making a personal sacrifice.

An important episode that explores how society treats the aged and infirm as well as a direct allegory for Alzheimer's, the episode was packed with powerful moments, with Lenard and Stewart at the top of their game. One of several highly rated episodes that year, "Sarek" helped make the series' third season one of its very best.

3. Relics (The Next Generation)

By the sixth season of "Star Trek: The Next Generation" the series had featured a pair of prominent crossovers, but there was still one more venerated visitor to come. "Relics" brings back the original Enterprise's chief engineer Montgomery "Scotty" Scott (James Doohan) for one of the most crowd-pleasing episodes of the show's entire run. There was no time-travel needed here, as the writers came up with a clever way to literally transport Scotty from one generation to the next.

The episode opens with Picard and the Enterprise-D detecting a distress signal coming from the surface of a Dyson sphere — an artificial globe constructed around a star. When they go aboard, they are shocked to discover a transporter pattern that's been trapped in the system for nearly 75 years. When they re-materialize it, it's none other than Scotty. Now aboard an all-new Enterprise, Scotty finds himself a man out of time and he struggles to find a place for himself. But when the Enterprise becomes trapped inside the sphere, it's up to the two Enterprise engineers — Scotty and Geordi LaForge — to save the day.

"Relics" was filled with iconic moments, including a signature scene set on the holodeck where the bridge of the original Enterprise was lovingly recreated. But it's also an episode that looks at what it means to get older, making it both a touching installment and a fun crossover.

2. Unification (The Next Generation)

When "The Next Generation" first launched, many might have expected to see the series lean on its iconic ancestor with a parade of guest appearances from classic characters. But producers wanted the series to forge its own path without relying on connections to its predecessor, so they largely stayed away from such crossovers. But following the successful episode "Sarek," they dabbled in a bit more nostalgia. The series' fifth season features arguably its biggest guest star ever: Leonard Nimoy as Mr. Spock.

A much-hyped two-part installment, "Unification" begins with the stunning announcement that Ambassador Spock has gone missing and may have defected to the Romulans. With orders from Starfleet to track down the wayward Vulcan legend, Picard and Data go undercover on Romulus. There they find a dissident movement hoping to reshape Romulan politics with the goal of reunifying their society with their Vulcan cousins. Spock is there not as a defector, but as a deeply invested member of the Romulan underground who hopes to help the dissidents gain acceptance. But not all is as it seems, and Spock and Picard soon discover a secret Romulan plot that could tip the balance of power in the quadrant.

Beyond Spock's return and the thrilling political intrigue, "Unification" also saw the return of the Romulan Commander Sela, played by Denise Crosby. In one of the finest hours of "TNG," Nimoy was in top form, with some of Spock's best moments coming in scenes opposite Picard and Data. 

1. Trials and Tribble-ations (Deep Space Nine)

There has been no better or more expertly executed crossover in "Star Trek" than in the legendary "Deep Space Nine" adventure "Trials and Tribble-ations." Not just because it sent the crew of the station back in time to the original "Star Trek" era; not just because it revisited one of the most beloved episodes in the franchise, but because the episode was well-written, lovingly produced, and just plain fun. 

A near-perfect episode, it used a mix of archival footage and then-cutting edge CGI techniques perfected in movies like "Forrest Gump" to allow Sisko, Dax, Bashir, Worf, Odo, and O'Brien to interact with the likes of Kirk, Spock, Scotty, and Uhura. In this new adventure, a Klingon disguised as a human who was once beaten by Kirk travels back in time to the site of his defeat with a plan to assassinate the Enterprise's captain in the past. Sisko and his crew follow him back in time, revisiting the events of "The Trouble with Tribbles" and must find a way to stop Darvin without altering the timeline.

One of the highest-rated episodes of the series, it was thanks to a chance encounter at a pizza restaurant in California that producers were able to snag "Original Series" guest star Charlie Brill, who played Arne Darvin back in 1966, to reprise his role (via StarTrek.com). But make no mistake, "Trials and Tribble-ations" isn't just great because of the special effects or the crossover with Kirk — it's a fantastic all-around episode in its own right.