FromThe Walking DeadtoAmerican Horror Story, there are plenty of TV shows that use the tropes and techniques of the horror genre to frighten their audience. But TV terror isn’t just limited to horror shows. In fact, it can be even more terrifying for a non-horror series to do a horror episode, because the audience isn’t expecting it.

FromAtlanta’s “Teddy Perkins” toThe Simpsons’ “Halloween of Horror” toBoJack Horseman’s “The View from Halfway Down,” there are plenty of episodes of otherwise harmless shows that left viewers feeling deeply unsettled.

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RELATED:These Modern ‘Simpsons’ Episodes Are Worth Checking Out

Halloween Of Horror (The Simpsons: Season 27, Episode 4)

Every year since season 2,The Simpsonshas released an annual Halloween episode dubbed “Treehouse of Horror.” The segments of these anthologies have parodiedhorror classics ranging fromThe ShiningtoA Nightmare on Elm Street. In its most recent season, for the first time ever,The Simpsonsaired two Halloween specials: the regularly scheduled “Treehouse of Horror” episode and a parody of Stephen King’sItentitled “Not It.” But none of those episodes compare to the show’s true scariest installment: season 27’s “Halloween of Horror.”

This episode is moreThe StrangersthanThe Simpsons, as disgruntled Halloween store employees break into the Simpson household to terrorize Homer and Lisa. This is the onlySimpsonsepisodethat’s more interested in terrifying its audience than making them laugh.

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Untitled (Louie: Season 5, Episode 5)

The fifth season ofLouieended up being its last before Louis C.K. was accused of sexual misconduct and FX cut ties with the comedian. Season 5 delivered some of the show’s funniest episodes, but its most surprising installment barely features a single joke. Instead, it’s a series of recurring nightmares in which Louie is plagued by the boogeyman. It starts off as a pretty typical episode until Louie falls asleep in the back of a cab. Cut to him waking up in his apartment, unsure of how he got there. There’san eerie sense of Lynchian surrealityas there’s a knock at the door and Louie opens it to see nothing – not even the hallway; just pitch black.

And then, out of the blue, a terrifying beady-eyed naked man lunges out of the darkness and attacks him. From that moment on, viewers have no idea if they’re watching the waking world or another disturbing dream sequence until that beady-eyed man pops up for another jump scare.

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The View From Halfway Down (BoJack Horseman: Season 6, Episode 15)

Inthe penultimate episode ofBoJack Horseman, “The View from Halfway Down,” BoJack attends a surreal dinner party hosted by his mother and attended by all the show’s dead characters. About two-thirds of the way into the episode, BoJack realizes he’s stuck in limbo after drunkenly stumbling into his swimming pool and drowning. “The View from Halfway Down” is terrifying on an existential level. Throughout the episode, the looming specter of death is symbolized by the black tar seeping across the screen (a callback to an earlier episode). “The View from Halfway Down” is full of haunting moments from deceased characters, like Sarah Lynn’s reprisal of the song “Don’t Stop Dancing ‘Til the Curtains Fall” and Herb telling BoJack there is no “other side.”

The most chilling part of the episode is its ambiguous ending. Netflix viewers knew they still had one more episode to go, but the flatlining heart monitor that plays over the closing credits had fans fearing they’d seenthe untimely end of BoJack.

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Teddy Perkins (Atlanta: Season 2, Episode 6)

One of the most shocking and experimental episodes ofAtlantadeviates from the show’s usual comedic approach for a half-hour of horror. Season 2’s “Teddy Perkins” begins with series regular Darius traveling to a mysterious mansion to pick up a free piano advertised on a message board. There, he meets the title character, a creepy, pale man with a mask-like face, played byseries creator and lead Donald Glover.

From the second Darius arrives at the mansion, director Hiro Murai creates a palpable sense of dread. It’s clear from the offset that there’s something very strange about Teddy, but what that is doesn’t reveal itself until the unsettling climax of the episode.

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Starting Now (Barry: Season 3, Episode 8)

Bill Hader’s hitman comedyBarryhas always had a dark, twisted sensibility, but ittook a decidedly dramatic turn in season 3. When the third season began, Barry’s killing spree in season 2 seemed to have broken him mentally. Within the first couple of episodes, he’d gone back to contract killing and threatened to murder Gene’s son to force him to say, “I love you, Barry.” But the season finale, “starting now,” took the terror to another level entirely.

This episode plays more like a psychological thriller thananyBarryepisode that came before it. Every scene was a nail-biter, from Sally’s first kill to Jim Moss’ intense interrogation of Gene to Hank’s near-miss with a panther.