The 10 Most Devastating Sci-Fi TV Episodes of All Time, Ranked

In truth, any of the episodes that I previously mentioned could take the top spot, but there is one undisputed heavy sci-fi episode that can claim the top spot without any arguments. "Home," a Season 4 episode of the iconic sci-fi series The X-Files, was famous for moving away from the typical "monster-of-the-week" storyline of the series, and, instead, was heavily focused on folk horror to tell a story that still haunts everyone who's seen it.

"Home" finds our protagonists, FBI agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) investigating the death of a deformed infant, only to discover that this investigation would lead them to a reclusive, mutant family that calls a booby-trapped farmhouse home. The episode was so intense, so graphic, that it became the first episode ever to be rated TV-MA. It was also banned from being rerun due to its disturbing nature for three years, making this episode truly a heavy one that was creepy and bold at the same time. If you have the mental strength to watch "Home," you’ll understand why this episode deserves to be number one on this list.

While the latter seasons of the hit sci-anthology series Black Mirror can be a bit hit-or-miss, the first four seasons of this genre-pushing show didn’t miss once. While Season 1 perfectly set the tone for what Black Mirror would be about, it was Season 2 where the show really hit its stride, especially when it came to heavy episodes that spoke about technology's impact on humanity. Take the Season 2 episode "White Bear," for instance, where it dispensed a twist that no one saw coming.

"White Bear" followed a woman who, after losing her memory, wakes up to find that a mysterious signal has turned the British population into mindless, mute voyeurs, whose sole purpose was to record everything on their phones. But, here was the twist: it was all a ruse, a punishment for a woman who killed her child. The overall message of "White Bear," that we as a society take pleasure in seeing people punished for their awful deeds, was extremely deep and thought-provoking, making this episode one of the heaviest sci-fi episodes ever created.

When it was announced in 2004 that Battlestar Galactica would be rebooted, to say the excitement was palpable is an understatement. Fans had been waiting years for a proper reboot of the beloved but short-loved '70s sci-fi series, and right from the start, it was clear that the modern reboot of Battlestar Galactica would be fantastic and deep. The episode that kickstarted everything was "33," an episode that was so intense and so filled with tension, that it's considered, without question, one of the best sci-fi episodes in television history.

"33" perfectly captured the realistic nature of the genre, one that focused more on the endurance of humanity rather than showcasing the advanced technology that the series was wrapped around. "33" was raw and gritty, and it was, above all else, character-driven. We saw, in painful detail, the toll the Cylons deadly attack had on the crew — the sleep deprivation they went through and the mental anguish the attack took on the crew. It convinced the SyFy Network that Battlestar Galactica was worth taking a chance on, and they were smart to do so.

For 90 minutes in 2016, we were treated to one of the best modern-day heavy sci-fi episodes ever to grace the television screen. The show that birthed it was Westworld, the HBO adaptation of the underrated 1973 classic that successfully expanded on the world Michael Crichton created. In some respects, you can say that the entire series of Westworld dabbles in heavy sci-fi, with the ever realistic theme of AI and how it has made a substantial impact on human society.

This is best showcased in the Season 1 episode "The Bicameral Mind," which tells the story of how the androids became truly self-aware, which was by recognizing their "internal monologue," or, to put it another way, they listened to their "God." This was seen on Maeve's (Thandie Newton) decision to return to the park to find her daughter, which was a representation of breaking from her scripted programming and becoming self-aware. "The Bicameral Mind" successfully wrapped up the philosophical storyline of Season 1, and it was a perfect way of sending the season off on a great note.

Since it first premiered on the BBC in 1963, Doctor Who has been a constant staple of the sci-fi genre. The series is well-known for delivering on high-concept storylines, with the Season 9 episode "Heaven Sent" being among one of the show's strongest examples of how the series delivered on its concept. The episode is unique in the fact that it was basically a solo performance from Peter Capaldi, and it found the good Doctor trapped in a "confession dial" that aims to torture and bring out secrets from all those who enter it.

"Heaven Sent" hit some powerful themes such as endurance and grief, wrapped around recurring time loops that hit in a different way than the standard Doctor Who episode. It definitely was a heavier episode with a story arc that packs quite an emotional punch, thanks in large part to Capaldi's performance. To this day, "Heaven Sent" is widely considered the best episode in this series' storied history.

While sci-fi shows did exist before The Twilight Zone premiered on CBS in 1959, it was this anthology series created by Rod Serling that brought the genre into the mainstream on television. The first season of The Twilight Zone is widely considered a masterpiece in building tension, which was perfectly executed in the Season 1 episode "Time Enough at Last," which was adapted from a short story written by Lynn Venable.

In this episode, a man named Henry Bemis (Burgess Meredith), who works as a bank teller and loves books, emerges from his bank vault to find the world has been destroyed by a nuclear war. Initially depressed, he finds the ruins of a public library that still had its books intact. While this soothes his depression, knowing he can read in peace and without anyone interrupting him, he shatters his glasses, which makes him depressed again. "Time Enough at Last" espoused the fears of the Cold War-era with an iconic "monkey's paw" storyline in that he was granted his wish to read in peace, but it came at the devastating price of isolation and loneliness in a destroyed world. This is still regarded as one of the show’s best episodes, and one of its heaviest.

Two years after Arcane came to an end, we still talk about this show and for good reason. The Netflix series was simply spectacular, both in its visuals and its incredible storyline. The way it brings together emotion and moral themes together in a sci-fi setting, makes Arcane one of the most influential shows in modern television history. We could have honestly had multiple episodes from Arcane on this list, but the more I thought about it, the more the Season 1 finale, "The Monster You Created," was the best call to make here.

With tension between the cities of Piltover and Zaun reaching a boiling point, we see Powder (Ella Purnell) fully embrace her chaotic transformation as Jinx, resenting her sister, Vi (Hailee Steinfeld). The heavy theme of trauma and neglect creating "monsters" is so in-your-face, it's practically hard to ignore. And, if to drive the point of the Season 1 finale home, the ending song, "What Could Have Been," sung by the legendary Sting, is emotional and powerful.

OK, let's get this out of the way first and foremost. Yes, we know that the hit CW series Supernatural is more of a dark fantasy show than a sci-fi series; but, it does have tropes and themes that are also tied to sci-fi shows, which gave us some leeway to put the Season 5 finale "Swan Song" on this list. Not only was this one of the best episodes of the entire series, but it was also meant to be a series-ending episode. Stay with me for a second as I explain.

Originally, Supernatural was only supposed to be a five-season-long series, with an extremely high-stakes and action-packed finale to send the series off with a bang. That's how the episode ended up with the title "Swan Song," as this was supposed to be the Winchesters' goodbye to the Supernatural universe. WIth Lucifer (Mark Pellegrino) taking over Sam's (Jared Padalecki), the younger Winchester sacrifices himself to save Dean (Jensen Ackles) and the world by jumping into the cage with Michael (Jake Abel). As we know now, Supernatural didn't end with "Swan Song," but the episode was designed with such a heavy, emotional rift, that if the network had allowed Eric Kripke to end the series there, as he wanted, it would easily be one of the heaviest, greatest season finales of all-time, no questions asked.

One of the most underrated sci-fi series of the modern-era, Love, Death + Robots is a masterclass of how to weave multiple genres together to create a series that will make you laugh, scared, and have you in deep thought, sometimes all at once. But in the Season 1 episode "The Witness," Love, Death + Robots ditched the comedy and went for an episode that was extremely heavy on the story it wanted to tell, and it succeeded in that mission.

"The Witness," directed by Alberto Mielgo, used a non-linear, looping narrative to tell the story of a woman who witnessed a murder, and is pursued by the murderer. It seems like a straightforward episode, right? A woman sees a murder. The killer is trying to "silence" the witness. The witness fought back. We've seen this trope play out countless times before; but, what makes "The Witness" so unique was the looping narrative, in which the witness and the killer swap places in an infinite cycle. That's right, the witness becomes the killer, and the killer becomes the witness, and this cycle plays on and on. What this narrative does is explore, in visual depth, the cycle of violence that plagues our society. It was a fantastic episode, and one that will certainly sit on your conscience after the end credits roll.

When viewers first laid eyes on the Apple TV sci-fi series Foundation, people knew right off the bat that this show was going to be different. I will forever have tremendous respect for TV shows that come out swinging, and "The Emperor’s Peace," the pilot episode of Foundation, did exactly that and then some. A good sci-fi pilot should always aim to establish the world that the viewer will be immersed in, and that world in Foundation is absolutely jaw-dropping.

The sheer scale of "The Emperor's Peace" set the tone for the show, as it grappled with the tension between religion and science. In fact, it's a theme that we're kind of seeing play out in our own timelines, which lends the struggle in the series-opener a certain kind of realistic gravitas that separates it from its counterparts. Add in the stellar performances from Jared Harris and Lee Pace, and you will find yourself in deep thought after watching "The Emperor's Peace."