Contains spoilers for all the shows mentioned.long-running shows that maintain their quality from start to finish, the storied genre has something for every brand of fan out there, whether the show takes the form of a timeless classic or an exciting new kid on the block.

The genre has always influenced wider popular culture in a way that cannot be taken for granted, and the best single sci-fi television episodes that have ever aired are part of the reason. With remarkable levels of quality, memorability, and lasting impact, many of these episodes are also widely regarded as some of the most impressive pieces of television ever brought to life onscreen regardless of their parent genre.

10 The Rescue

The Mandalorian

While The Mandalorian may have started to run out of steam with its third and most recent season, the show is still loaded with stellar entries that prompted many fans to label the Pedro Pascal-led space Western as one of the best Star Wars television shows. The Mandalorian's best episode is unequivocally the second season finale, "The Rescue," depicting Mando's attempts to free Grogu from the clutches of Giancarlo Esposito's Moff Gideon.

From the episode's stunning action sequences to the triumphant arrival of a digitally de-aged Luke Skywalker to save the day at the last minute, The Rescue channels all the tried and tested elements that have historically produced the best Star Wars films and television shows with knockout results. The most emotionally loaded episode of the show to date, the tear-jerking scene depicting Pascal's charge removing his helmet to bid Grogu farewell serves as the cherry on the cake for one of sci-fi's finest episodes.

9 The Inner Light

Star Trek: The Next Generation

Universally regarded as one of the greatest episodes in the entire Star Trek franchise, Star Trek: The Next Generation's "The Inner Light" has been receiving glowing reviews from fans and critics alike since debuting in 1992.

The penultimate episode of the show's fifth season, The Inner Light follows Patrick Stewart's Captain Picard after he is knocked unconscious by a mysterious alien probe, causing him to inexplicably experience a lifetime worth of another man's memories in just under half an hour.

Clocking in with an exemplary score of 9.4, The Inner Light is the highest-rated episode of Star Trek: The Next Generation on IMDb.

The personal favorite episode of Star Trek icon Stewart, "The Inner Light" weighty themes and hauntingly poignant ending have been inviting deep philosophical and existential introspection for more than three decades. A timeless classic that sees the iconic franchise at its very best, the episode has aged like a fine wine to stake its claim as one of the greatest segments of sci-fi television ever conceived.

8 One Way Out

Andor

Arguably the best Star Wars television show of all time, critics' darling Andor serves as an origin story for the titular character, Diego Luna's Cassion Andor. Contentiously the darkest and most mature take on the franchise's traditionally lighthearted subject matter to date, the first season received rave reviews from critics, with the show's tenth episode, "One Way Out," singled out for particularly effusive praise.

Touted as one of the best episodes of the year irrespective of genre, "One Way Out" chronicles a daring escape from the Narkina 5 Prison Complex. Leveraging an Emmy-worthy performance from Andy Serkis that sees The Lord of the Rings' standout deliver one of the most epic sci-fi speeches in the history of popular culture, the episode's thrilling rebellion scenes and emotional heft make for invariably magnificent television.

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Boasting a perfect 100% approval rating on Rotten Tomatoes, "One Way Out" is perhaps the single greatest factor in legitimizing Andor as a standout Star Wars offering.

7 The We We Are

Severance

Drawing the absolute best out of an inspired premise and the considerable talents of an ensemble cast, Severance has proved to be one of the most engrossing and ambitious shows that current television has to offer. Depicting a dystopian reality where employees undergo "severance" to have two entirely separate personalities, one for work and one for their social life, the show's first two seasons have received effusive praise.

Many highlighted the first season finale, "The We We Are," as the current gold standard. Featuring a riveting narrative to complement the show's usual wicked humor and first-rate performances, "The We We Are" chronicles one of the series' most important developments as Dylan activates the overtime contingency protocol.

Rubberstamping Severance's credentials as one of television's best new shows, the explosive crossover between the "Innies" and the "Outies" that ensues makes for blockbuster viewing of the highest order, a state of affairs that is aided by one of the genre's more memorable cliffhangers.

6 33

Battlestar Galactica

Introducing one of sci-fi's most beloved television shows with a bang, Battlestar Galactica's pilot episode, "33," set the bar for what would go on to become one of the genre's most acclaimed outings. Touted as a reimagining of the cheesy 1978 original show of the same name, the sci-fi drama picked up where its introductory 2003 miniseries had left off, wasting no time in establishing a considerably more grounded air to proceedings that would persist for the remainder of the show's run.

Thrusting the Galactica and a host of refugee spaceships into a visceral fight for survival straight off the bat, the show's lauded first entry sees the convoy ruthlessly attacked by Cyclons without fail every 33 minutes, with the unrelenting attacks leaving the sleep-deprived defenders in a delirious state of exhaustion. A white-knuckle, subversive thrill ride of the highest order, "33" remains one of the most impressive pilot episodes of all time.

5 The Bicameral Mind

Westworld

While the dystopian drama Westworld may have ultimately proved to be one of sci-fi's most frustrating "what if?" stories, the show's debut still stands as one of the most impressive single seasons of television in recent memory. The show's crowning achievement took the form of Westworld's first season finale, "The Bicameral Mind," a magnificent hour-and-a-half segment of television that stands as the series' best episode by a considerable distance.

Loaded with jaw-dropping reveals and mind-bending twists, The Bicameral Mind tied up the first season's array of complex narrative threads in a seamless fashion. Featuring knockout performances from Anthony Hopkins, Evan Rachel Wood, and Ed Harris, "The Bicameral Mind" delivers answers to an array of Westworld's most pressing questions in such a satisfying manner that there's a notably cathartic air to proceedings, despite the episode ending with an electrifying cliffhanger for the ages.

4 San Junipero

Black Mirror

An indispensable entry in the annals of sci-fi history, the lauded anthology series Black Mirror has produced a selection of seminal television episodes since debuting in 2011. USS Callister, Hang the DJ, and The Entire History of You are just a few of the hit show's most revered offerings, but Black Mirror's single best episode to date has undoubtedly proved to be Season 3's evocative fourth entry, "San Junipero."

Chronicling a stirring romance set against the backdrop of the titular simulated reality, a space designed for the elderly and the deceased, "San Junipero"'s uplifting conclusion is a heartwarming testament to the fact that the notoriously nihilistic Black Mirror's best episodes aren't always the ones that end in doom and gloom. Inviting deep personal introspection through its evocative subject matter and committed performances, Black Mirror's first same-sex love story rarely fails to tug on the heartstrings.

3 Long, Long Time

The Last Of Us

It's a supremely ironic state of affairs that the finest episode of HBO's triumphant take on Naughty Dog's The Last of Us doesn't actually feature the main characters as its central focus. Expanding on the origin story of a minor character from the video games instead, the third episode of the post-apocalyptic sci-fi drama is a stirring tale of finding one's soulmate in the unlikeliest of places, chronicling the tender relationship that unfolds between Nick Offerman's Bill and Murray Bartlett's Frank.

While the video game relegated the pair to the minor roles of a nutty doomsday prepper and a dangling corpse respectively, HBO's decision to turn this minor story thread into one of the most evocative tales of love and connection in modern television history proved to be nothing short of inspired. Universally acclaimed by critics as The Last of Us season 1's best episode, "Long, Long Time" saw its leading duo receive Emmy nominations and has been touted as one of the best television episodes in recent memory.

2 The Massacre At Hawkins Lab

Stranger Things

Turning in the most impressive installment of Netflix's flagship title to date, the fourth season of the sci-fi horror smash hit Stranger Things was notable for featuring several of the acclaimed show's greatest episodes. However, while installments like Dear Billy were lauded by many as near-perfect segments of television, Stranger Things' finest example came with the revelations-loaded midseason finale, "The Massacre at Hawkins Lab."

"The Massacre at Hawkins Lab" is the highest-rated episode of Stranger Things on IMDb, boasting a rating of 9.6.

Producing an explosive cliffhanger to end Volume 1, the episode saw Joyce and Hopper reunited for the first time following his apparent death in the previous season. However, this development would prove to only be the entrée; the mind-blowing reveals of Vecna's true identity and Eleven's experiences at the lab provided answers to questions that many fans had been waiting on for years.

Serving as an enthralling hook of the highest order, this episode is arguably the Duffer Brothers' finest entry to date, expertly stoking the fires of fan base anticipation for the premiere of Volume 2.

1 The Constant

Lost

Widely acknowledged as one of the greatest television shows of all time, it stands to reason that Lost's best episode would stand as one of the best single sci-fi television episodes that has ever aired. A mind-bending, time-traveling love story for the ages, Season 4's "The Constant" was universally lauded by fans and critics alike, with many going as far as to label it as one of the most flawless pieces of television ever conceived.

Following Desmond's desperate attempts to anchor himself to the present by finding his "constant," the episode's award-worthy performances, masterful cinematography, and rousing conclusion complement a meticulously designed central narrative thread to produce a faultless viewing experience.

Throw in one of the iconic series' most heartwarming moments in the form of Desmond and Penny's spine-tingling reunion over the phone, and few contenders can rival this seminal sci-fi television episode.