Created by J.J. Abrams, Alex Kurtzman, and Roberto Orci, the cult sci-fi series Fringe stands as one of the genre’s best TV shows of all time, at least according to Rolling Stone. The series relied on a mix of monster-of-the-week episodes and mythology episodes for most of its run and managed to set itself apart by often intertwining the two storylines in a surprising but highly effective manner. The five-season-long tale of Peter, Olivia, and Walter, parallel universes, visitors/invaders from the future, shapeshifters, doppelgangers, and weirdness in spades has given us countless fantastic hours of television.

Today, we’re counting down the show’s ten most groundbreaking episodes. Before we begin, we’d be remiss not to list a few honorable mentions, so here goes: “There’s More Than One of Everything”, “The Day We Died”, “Worlds Apart”, and “An Origin Story”.

“LETTERS OF TRANSIT” (SEASON 4, EPISODE 19)

In season four, Fringe’s special episode nineteen was extra special. Instead of taking a detour from the main story and taking us down an unexpected and endearingly weird path, “Letters of Transit” took us to the future. In the brave new world, the Observers have taken over and the weakened Resistance is still fighting the good fight. We meet Peter and Olivia’s now all-grown-up daughter Etta and her friend Simon, who are on a mission to free the amber-encased bodies of the Fringe team.

The writers made a bold and risky move with this nutty number nineteen, which paid off in the long run as the entire fifth season was built upon it. Sure, it was an odd installment at the time it aired, but even then one had to appreciate the inventive storytelling, the excellent cast additions, and most importantly the guts to do something like this so close to the conclusion of the show’s season four main arc.

“BROWN BETTY” (SEASON 3, EPISODE 19)

Having upended the status quo in episode eighteen, the writers took the 19th Episode Tradition to a whole new level with “Brown Betty” – a noir fairy tale musical. Naturally, reactions were mixed, however, we’d argue that episodes like this are what made Fringe such a phenomenal show.

It takes courage and ingenuity to say “hey, universes are colliding, but let’s do a musical episode”, and for that alone, the writers earned our respect and admiration. Amazingly, this offbeat story set in a world that looks like the 40s but has advanced technology, in which Olivia is a P.I., Peter has an artificial heart, and everyone – including the corpses in Walter’s lab – sings works. And, while it doesn’t advance the plot, it does connect to the real world. This story is told by Walter (on drugs) and he imagines himself as the villain, reflecting his guilt and despair over Peter. On the other hand, it gives Peter and Olivia the chance to live out a semi-normal romantic story, which they’re not able to do in the real world. “Brown Betty” is truly the weirdest and most underrated Fringe episodes.

“AND THOSE WE’VE LEFT BEHIND” (SEASON 4, EPISODE 6)

In season four, Peter Bishop found himself in a strange new world, one in which the people he knew and loved didn’t know him. Even trying to imagine what that must have felt like is enough to make our skin crawl. In one of the show’s most emotional and resonant episodes, “And Those We’ve Left Behind”, the writers manage to craft a story that poignantly reflected Peter’s feelings.

In this episode, a scientist isolates his house in a time bubble in order to go back in time to when his wife wasn’t yet experiencing symptoms of Alzheimer’s and encourage her to finish her research to permanently stabilize the bubble. Watching him desperately attempting to hold on to the woman he loves, and who’s now become but a shadow of her former self is made all the more heartbreaking when you realize that Peter’s going through a similar situation with Olivia.

“OVER THERE: PART 1 & 2” (SEASON 2, EPISODE 22 & 23)

In the two-parter season two finale, “Over There”, we get to properly explore the other universe and the characters that inhabit it for the very first time. With Walternate planning to use Peter to destroy our universe, the stakes are higher than ever. Our Walter comes up with a plan to turn the Cortexiphan kids into the Suicide Squad, sending Olivia and the former freaks-of-the-week Over There to bring Peter back.

Fringe does an amazing job at presenting the otherness of Over There with quirky pop culture references and tidbits of alternate history, without breaking away from its character-driven storytelling. We get to meet the Alt versions of Olivia, Walter, Charlie, Lincoln, Astrid – and special praise goes to the actors for doing such an outstanding job at differentiating between their characters. The finale ends with a major cliffhanger where Fauxlivia is sent to Earth-1 with our Fringe Division, while our Olivia is captured on Earth-2. “Over There” was a brilliant culmination of the mythology arc up to that point and it set up the season widely considered to be the show’s best.

“THE PLATEAU” (SEASON 3, EPISODE 3)

In season three, Fringe divided its episode between Over Here and Over There. “The Plateau” is arguably the best standalone episode set Over There, and it follows the team as they investigate a case in which a man named Milo goes on a killing spree Rube Goldberg-style using just a pen. It turns out, Milo got an IQ boost, allowing him to predict future events by calculating the probabilities.

In the exciting climax, Milo calculates that Olivia will die chasing him, however, since she’s not from this universe, Olivia ignores a health warning, keeps running, and manages to capture Milo, something he could never have predicted. This, in turn, alerts Olivia that she might be in the wrong place, a suspicion made even stronger by the vision of Peter. Not only is “The Plateau” brilliantly written, directed, and acted, it also resonates with the overarching premise of season three, which boils down to one bad guy causing chaos by inciting others to do what comes naturally.

“LYSERGIC ACID DIETHYLAMIDE” (SEASON 3, EPISODE 19)

The so-called Episode 19 Tradition revolves around the concept that the nineteenth episode of any season of Fringe is weird even by Fringe standards. In season three that was the episode “Lysergic Acid Diethylamide”, an animated episode set inside the brain of Olivia Dunham.

With William Bell’s consciousness still occupying Olivia’s body and Olivia’s life hanging in the balance, Walter comes up with a plan for him and Peter to enter Olivia’s mind with a little help from LSD (because this is Fringe and LSD is the ultimate solution to any problem) in order to locate her ego for it to regain dominance in her mind. Meanwhile, Broyles drops acid at the lab and has a hilarious trip. “Lysergic Acid Diethylamide” is one of the weirdest, most ambitious, and most innovative episodes Fringe has ever done, and it’s one of the finest hours of television the show has given us.

“WELCOME TO WESTFIELD” (SEASON 4, EPISODE 12)

In this standout episode that bears an uncanny resemblance to the outlandish X-Files installments, a plane is brought down by a strange magnetic disturbance, sending our trio to Westfield. It soon becomes obvious that something horrific is afoot in this small town, as the residents appear to be drifting in and out of different personalities. On top of that, every time you drive out of Westfield, you drive right back in.

So, the inescapable town is shifting from one version of itself to another, which mirrors what’s been happening to Peter, Olivia, and Walter in season four. Peter’s sudden arrival into this universe has started to make Oliva and Walter more like the ones he knows and loves, indicating that perhaps he’s not supposed to find a way back home, but that home is finding its way back to him. And that’s what makes this fantastic weird-of-the-week episode one of the show’s best installments. Plus, it went back to basics with the original team out in the field investigating the latest weird event.

“MARIONETTE” (SEASON 3, EPISODE 9)

“Marionette” is quite possibly the single most depressing and frightening episode of Fringe. The team comes across a disturbed scientist, Roland, who attempts to resurrect his deceased love interest by harvesting her donated organs and, quite literally, stitching her back together. He manages to do so and we get the most unsettling image of a stitched-up corpse propped up on wires. But as he looks into her eyes, Roland realizes it’s not really her. And that right there is part of what makes this episode truly special.

Roland’s disturbing but emotionally resonant story thematically parallels with Peter and Olivia’s current tragic arc. Learning of Peter’s relationship with Fauxlivia, who essentially stole her life, Olivia struggles to understand how Peter didn’t realize it wasn’t her. Which is why Roland’s words hit home with Olivia who confronts Peter about it in one of the show’s most heartbreaking scenes. The writers managed to craft a truly heartfelt and believable relationship drama and integrate it flawlessly into a monster-of-the-week episode, which is remarkable.

“WHITE TULIP” (SEASON 2, EPISODE 18)

Anyone who’s seen Fringe knows that white tulips symbolize forgiveness, and it’s all thanks to Walter. In the landmark mythology episode and exceptional standalone episode, “White Tulip”, we’re first introduced to the eponymous flower, which became a recurring motif. “White Tulip” is a master class in integrating mythology elements into a standalone episode, and a damn good one at that.

While Walter struggles to tell Peter the truth of who he is, the team investigates the consequences of a man traveling back in time on a desperate quest to save his fiancee. The way the two storylines intertwine strikes an emotional chord, as both stories get a bittersweet resolution. The fresh take on Walter’s story, his guilt, and his grief provided through the foil of a man stuck in a similar position is nothing short of brilliant. That final shot of Walter holding the drawing of a white tulip is one of the series most poignant and memorable moments.

“PETER” (SEASON 2, EPISODE 16)

In this season two episode, we take a trip down memory lane when Walter recounts the story of Peter’s secret origin to Olivia. Flashing back to 1985 together with the awesome 80s-inspired opening credits, the episode reveals what exactly happened to Peter, what role September played in all of it, and how Walter’s actions set everything that’s been happening into motion.

“Peter”, first and foremost, is a superbly written episode that ties the mythology up to that point of the show perfectly by providing much-sought-after answers. But, on top of that, it’s an incredibly emotional, moving, and heart-rending hour of television, mostly thanks to John Noble’s outstanding performance. “Peter” opened the door for the show’s future brilliant storytelling involving the alternate universe, and it’s rightfully considered a quintessential Fringe episode, as well as the episode that cemented it as one of the greatest sci-fi series of all time.