The 20 Most Significant Episodes of Lost

Twenty years ago, Ocean Flight 815 crashed on prime-time television and permanently altered viewers’ expectations of the medium. When Lost debuted on ABC on September 22, 2004, it was rare to see a serialized mystery on network TV. It was even more rare to see an episode made with as much ambition and cinematic scope as the pilot, which, at the time, was the most expensive first episode in television history at a cost of around $13 million. More than 18 million people tuned in to that debut, and a pop-culture phenomenon was born. Fans picked apart each episode week by week, relishing the opportunity to solve the mysteries surrounding the island and the Dharma Initiative that once called it home.

Throughout six seasons, Lost had its ups and downs in quality. The publication of a chapter about the show in Maureen Ryan’s 2023 book Burn It Down revealed what a challenging, cutthroat workplace it had been for some of the writers and actors who felt bullied and demeaned because of their race or gender. It’s challenging to watch or rewatch the show now (something that can be done as of this week on Netflix) without reflecting on the behind-the-scenes baggage Lost carries with it. But the passage of time also liberates us from the expectations viewers had during the show’s original run when everyone was so rabid for answers to its most minor questions — “I still don’t know how or why Walt made that bird crash into a window in season one, episode 14, and I need closure!” — that they sometimes couldn’t see the whole forest (jungle?) for the trees. Even allegedly pointless episodes can be fascinating to revisit in the context of Lost’s impact as a series that raised the bar for television just as the Peak TV era was beginning and social media was adding jet fuel to conversations about pop culture.

Obviously, it’s best to watch every episode of Lost in order, as the Smoke Monster intended, but if you’re trying to remember or understand why it was such an important and vital series, these 20 episodes should put that in perspective. Many of them are flat-out great. Some are not. But all are crucial to understanding what made, and still makes, Lost such a singular viewing experience.

After mentioning him for multiple seasons, Lost finally introduces Jacob, essentially the god of the island, whom we eventually learn has spent thousands of years trying to protect it from his twin brother, the Man in Black. “The Incident” is also a reminder of how consistently strong Lost’s season finales are; in this cliffhanger, the survivors, led by Jack, become determined to set off a nuclear bomb that will change the trajectory of events and prevent Oceanic Flight 815 from crashing. In an emotional closer, Sawyer lets go of Juliet’s hand as she falls underground — she survives the fall but repeatedly beats on the bomb with a rock until it seems to detonate, apparently killing Juliet in the process. Does their future-altering plan work? The episode ends without telling us: classic Lost.

Introducing new characters is a tricky thing on a well-established series (see the Nikki and Paolo–related item on this list), but Lost generally did a solid job even if the characters don’t always stick around. “The 23rd Psalm,” which focuses on the circumstances that brought onetime drug runner turned self-anointed priest Mr. Eko to the island, serves as a testament to that. Adewale Akinnuoye-Agbaje gives a commanding, sensitive performance as the hour flashes back to Eko’s relationship with his brother and his connection to the small plane Boone and Locke found on the island. In a loss for the series, Akinnuoye-Agbaje eventually asked to be written off the show because he reportedly didn’t want to stay in Hawaii, where production took place.

It was surprising in the first season when principal character Boone Carlyle dies after sustaining injuries from a fall. It was even more shocking when, just a few episodes into the second season, Boone’s stepsister, Shannon, is accidentally shot and killed by Ana Lucia, one of the newly introduced “Tailies,” the people in the back of the plane whom we learn in season two also survived the crash. Shannon’s death results in enormous heartbreak for Sayid, who had fallen in love with her. Whether you were for or against the Sayid-Shannon romance (not everyone was onboard when Sayid was supposedly still pining for the love of his life, Nadia), Shannon’s death doubles down on the promise made by Boone’s demise: Anyone on this island can go at any time.

This episode demonstrates just how deep into time-travel theory season five was willing to go. At one point, Daniel Faraday, the scientist played by Jeremy Davies, delivers an extended monologue about physics and how to potentially change the future that actually makes sense and sets the table for the season-five finale (“The Incident”) and the plot of season six. Very few shows of the time were able to integrate lofty scientific principles so organically into their story lines. I mean, The Big Bang Theory was nerdy, but Lost was “Let’s talk very seriously about scientific principles for ten straight minutes” nerdy.

It’s an understatement to say the final season of Lost was not universally well received, but this episode was the exception. By flashing wayyyy back to 1867 to explain how Richard Alpert landed on the island and eventually achieved immortality, “Ab Aeterno” proves that, even near the end, this series knew how to use its time-jumping supernatural framework to illuminate characters in surprising ways. Written by Melinda Hsu-Taylor and Greggory Nations, the hour reveals Richard first came to the island as a slave on the Black Rock, a ship that has been part of the show’s mythology since season one. The episode also caused behind-the-scenes tension when, according to Ryan’s book, showrunners Damon Lindelof and Carlton Cuse expressed resentment that Hsu-Taylor and Nations were the credited writers on such an acclaimed script. Hsu-Taylor recalled that they “basically [told] us how much we owed them for letting us have our names on that script. And they implied it would probably be good if we got them a little present.” Regardless of whatever was going on in the writers’ room, the onscreen result was terrific.

Lost’s most ruthless demonstration of its willingness to bump off key characters comes in this installment, when three of its beloved principles — Sayid, Sun, and Jin — die on an exploding submarine. The scene in which Sun and Jin refuse to leave each other as they drown is wrenching and beautiful, but it’s hard not to notice that all three victims are people of color who die in such quick succession that each individual doesn’t feel fully honored. The episode especially does not give the audience the proper space to process and mourn the loss of Sayid, the rare Muslim main character on prime-time television. Twitter was full of distraught people that night.

This still holds up as a thrilling two-part season finale, complete with a dynamite explosion in the Hatch, a kidnapping of four key characters, the reveal of the Others’ leader, and a twist ending that would haunt the imagination of Lost fans for a whole summer (as well as compel them to participate in The Lost Experience). But what’s most significant about this episode, which traces Desmond’s experience in the Hatch before the Flight 815 crew’s arrival, is that it actually does answer some vital questions, something Lost was often accused of not doing. After 20-plus episodes of watching the survivors input the numbers (4, 8, 15, 16, 23, 42) into an ancient computer every 108 minutes to keep the world from ending, “Live Together, Die Alone” confirms there was a valid reason for doing it. Not only is the island affected by electromagnetic forces, but those forces are likely what caused Oceanic Flight 815 to crash. This episode also establishes that Desmond’s relationship with Penny, whose family turns out to be more connected to the island than we knew, will be central to how Lost’s narrative reaches a resolution.

After a season-three finale that blasted open the show’s entire narrative structure, Lost’s viewership hit 16 million for its season-four premiere, the highest it would reach for the rest of its run. “The Beginning of the End” races ahead with the flash-forward premise hinted at in the final moments of the third season, peeking into a future where six of the survivors make it home and are dubbed the Oceanic Six. By finding a new angle on its well-established flashbacks vs. present-day structure, Lost enthusiastically tapped into a ton of new storytelling potential, something it would do again in seasons five and six.

In the Fan Service Hall of Fame, this episode has its own permanent exhibit. “Exposé” kills off the recently introduced, little-loved Nikki and Paolo, a reflection of the unusual relationship between Lost’s showrunners and its fans. Cuse and Lindelof became public figures to an unusual degree at the time, hosting their own weekly podcast about each episode and making it clear that they were absorbing feedback and genuinely trying to please fans. That’s not terribly unusual behavior now, but back then it was a novelty, as was the writers’ decision to bump off Nikki and Paolo, whom viewers openly disliked. (The pair were supposed to have been on the plane and the island the entire time, even though we never see them until season three.) The hour felt like filler, but it’s actually a fun departure episode that riffs on the TV thriller genre. It’s also rife with meta comments and inside jokes. Hurley: “Nikki’s dead.” Sawyer: “Who the hell’s Nikki?”

The Dharma Initiative, an organization that began studying the scientific properties of the island in the 1970s, is explained (sort of) for the first time when Locke and Jack sit down to watch an orientation video designed to train the people working inside the Hatch, a.k.a. Dharma’s Swan Station. This moment not only introduces tons of island history and mythology but is also a preview of all the Dharma details and Easter eggs fans would obsess over.

Lost wasn’t shy about killing off characters, but it also wasn’t afraid to turn small roles into bigger ones. The best example of this is Michael Emerson’s Benjamin Linus, the manipulative leader of the Others, who appears for the first time in “One of Them” as a man named Henry Gale who crash-landed on the island in a hot-air balloon. Emerson was originally slated to appear in three episodes, but he gave such an intense and slippery performance that Lost’s producers signed him up for more and eventually made him a regular. (He won a Supporting Actor in a Drama Emmy, too.) You can see why as soon as he shows up in this episode, sliding between victim and villain with such ease you’re never sure where to place him.

The three-part season-one finale is an exquisite, suspenseful collection that includes some of the most chilling moments in the show’s history (“We’re going to have to take the boy”) and the most moving (Vincent swimming after Walt on the raft still gets me). But the very end was what got people talking. The last shot gives us a view of Jack and Locke peering into the Hatch, an underground bunker that is a mystery for much of the season. But the episode never shows us what’s actually down there, forcing the audience to wait until the next season to find out. Some viewers were annoyed and thought this was a cop-out; others appreciated the sense of mystery. Those divided fan factions would continue to battle for the entirety of Lost’s run.

4, 8, 15, 16, 23, 42: Those numbers appear over and over on the island, but they’re first introduced in this episode, with a flashback focusing on a series of catastrophes that befall Hurley after he wins the lottery with them. Not only are the numbers crucial to the island’s mythology, they’re also an early indication of how much the show would rely on embedding deeper meaning into symbols and signs. This is also the episode in which Hurley emerges as a richer character with a backstory we could not have anticipated — he’s actually a millionaire and not just the funny guy who always says “dude”?

Season two opens with one of the great TV character reveals of all time: flashes of someone waking up, typing on a computer, working out, showering, making a smoothie, and, oh yeah, injecting themselves with some sort of medication while listening to “Make Your Own Kind of Music,” by the Mamas & the Papas. We can’t see the person’s face, and it’s not even clear exactly where this is happening until the camera pans down a hallway and up, where Locke and Jack are peering down the Hatch — exactly where we left them at the end of season one.

This sequence confirms that the Hatch is indeed a working bunker and there is at least one person living in it. That person is Desmond Hume, who will become as central to the dynamic on the island as the survivors we met in season one. So much of what made Lost Lost is represented in this episode: the argument referenced in its title about faith vs. skepticism, the etchings in the Hatch wall that scream out to be deciphered on message boards, the reveal that Jack and Desmond have, in fact, seen each other in another life, brother. It also earned the highest ratings of any Lost episode, with more than 23 million viewers.

Lost was such a national obsession ahead of its sixth and final season that the White House had to reassure fans that Barack Obama’s first official State of the Union address would not preempt the premiere. (It didn’t.) “LA X” introduces the flash-sideways for the first time, a version of events in which Oceanic Flight 815 never crashed, everyone lands in L.A., and their lives continue to progress and intersect from there. It’s yet another new way for Lost to mess with chronological storytelling, and it gave the show new juice in its final stretch. Just don’t talk about the stuff that involves the temple; it’s very boring.

Many consider this the finest hour of Lost ever made, and it’s tough to say they’re wrong. “The Constant” takes a challenging narrative premise involving Desmond mentally hopscotching between 1996, 2004, and the present and turns it into an accessible, elegant love story that should be regarded as a how-to guide for anyone trying to tell an emotionally resonant time-travel story on film. It also provides the most satisfying payoff in the show’s history when Desmond finally successfully makes contact with Penny via a phone call on Christmas Eve 2004. Kleenex are required.

Lost’s first really great twist doubled as an announcement that this series would use its flashbacks to change the audience’s perspective, not only regarding the characters but the island itself. “Walkabout” saves this flashback disclosure until close to the end of the episode, revealing that John Locke was wheelchair-bound and paralyzed from the waist down prior to the crash. Because Lost had not yet trained us to expect such surprises, this was a genuine gasp inducer. It also suggests right out of the gate that the island could be a source of healing as much as a haven for scary smoke monsters.

You hated the Lost finale. You loved the Lost finale. You didn’t like it at first but have recently reassessed it. However people may feel about the wildly hyped conclusion of the series, they have definitely talked, joked, and argued about it since it first aired in 2010. For better and worse, “The End” is one of the most debated and (by some) despised endings in television history, and the conversation around it will no doubt continue as long as human beings can discuss television. Just please, let’s all agree, once and for all, that they aren’t dead the whole time.

The idea for Lost originally came from ABC president Lloyd Braun, who wanted a scripted series with the same vibes as the reality hit Survivor mixed with a bit of Lord of the Flies and Gilligan’s Island. The concept eventually landed with J.J. Abrams, who was assigned Lindelof as a writing partner, and the two quickly developed a pilot script and show bible that outlined where the series might go in future seasons. Given its origins and the rushed timeline in which it was developed and shot, it’s remarkable that Abrams, Lindelof, and the rest of the cast and crew made a pilot so groundbreaking and immediately compelling. A two-parter, it establishes the show’s flashback approach, makes the audience feel immediately invested in the archetypal and therefore extremely recognizable characters, and prompts anyone watching to wonder what’s really happening on this island. “Guys, where are we?” Dominic Monaghan’s Charlie famously asks in this episode. Viewers might have asked themselves the same question. The Lost pilot was mainstream television with an ambitious self-assuredness we had rarely seen before.

If someone wanted to watch only one episode to get a sense of what Lost was about, this is the choice. The series’ most heartbreaking finale sends Charlie to the underwater Hydra station so he can unjam the signal that will allow the survivors to communicate with the outside world and hopefully be rescued. Charlie achieves what he sets out to do but drowns in the process, creating one of the most iconic images in Lost history and — sure, I’ll say it — television history in general, placing a hand with the words “Not Penny’s Boat” written on it against a glass window to warn Desmond that the people on a nearby freighter may not be their saviors after all.

But what really takes this episode to the next level is the ending, which gives us maybe the most iconic moment in Lost history: Jack Shephard, off the island and wracked with guilt about leaving, shouting to Kate, “We have to go back!” His breakdown confirms that what we thought was a Jack flashback was actually a flash-forward, a goosebump-inducing twist made all the more exciting because it came at the end of a bumpy third season that took a three-month hiatus. The finale also aired two weeks after ABC announced Lost would conclude with season six, an incredibly rare declaration for a broadcast TV show to make back then. By the time “Through the Looking Glass” aired, fans knew there was an endgame in sight, making the flash-forwards that much more exciting to contemplate. Even though some were ready to write off the show just weeks earlier, Lost proved it had some great storytelling left in it. Twenty years later, we’re still going back.