American Horror Story: Freak Show premiered last night, transporting the Fox horror anthology to a 1952 sideshow for its fourth season. If you watched the show, you’ll likely have the image of Twisty (John Carroll Lynch), a horrifying, murderous clown, temporarily burned into your retinas. But you’re not alone: Even creator Ryan Murphy is creeped out by what he’s wrought.

“I’m worried about people being too afraid of our clown,” Murphy told Buzzfeed in September. “It’s heart-stopping what he does. …I’m worried that people are going to have cardiac arrests.”

Short of being able to literally induce heart attacks, just how scary is “too scary?” Here are nine TV episodes that networks and distributors pulled for thoroughly frightening their audiences. Watch if you dare.

The X-Files: “Home”

The most controversial episode of The X-Files (and the first to garner a viewer discretion warning) is also considered one of its very best. Though critically praised, “Home” became the only episode of the series that Fox wouldn’t re-air after its 1996 premiere. The plot was disturbing, even by 2014’s jaded standards, featuring a deformed baby buried alive and incest galore. Lucky for fans, it was cleared for an X-Files cable marathon on FX the next year.

Cry Baby Lane

This 70-minute TV movie aired just once on Nickelodeon in 2000. Though a network rep would later argue that Cry Baby Lane was simply “forgotten,” it gained a cult following, thanks to the widespread belief that it had been banned from reruns because it was too scary. In fact, it was thought to be lost forever until a Redditor digitized and uploaded a VHS recording of the original broadcast. The plot centers on a creepy urban legend that comes true: the story of a pair of conjoined twins—one good, one evil—who were sawed apart after death. Naturally, the evil one comes to life (this is a horror movie, after all) and terrorizes a small town. If you’re feeling brave—or just really, really bored—you can watch Cry Baby Lane in its entirety on YouTube.

The Wicked Witch of the West on Sesame Street

In 1976, Margaret Hamilton reprised her role as Oz’s abrasive, green-skinned villainess on the PBS staple. She drops her broom while flying over Sesame Street, then tries every magical method at her disposal to get it back. Oscar the Grouch is smitten, and even Big Bird grows fond of her. Parents were less enthused. After an overwhelming negative response from viewers, who reported that she’d reduced their kids to “screams and tears,” Hamilton’s episode was permanently shelved. For what it’s worth, her appearance on Mister Rogers’ Neighborhood went over a lot better. But while we’re on the subject…

Mister Rogers’ Neighborhood: “Conflict”

Fotos International/Getty Images

In November 1983—right smack in the middle of that whole Cold War thing—the show aired a weeklong arc in which, through a series of misunderstandings, King Friday and Corny the Beaver stockpile enough nuclear weapons to ensure their mutual destruction. These episodes haven’t been aired since 1996. It’s to Mister Rogers’ credit that he intended this storyline as a sobering life lesson for the little world leaders of tomorrow, but still: too real.

Hannibal: “Œuf”

In “Œuf,” the episode of NBC’s gorgeously gruesome Hannibal that never quite saw daylight, a series of kidnapped children are brainwashed (by Molly Shannon!) into murdering their own families. What would have been the fifth episode of the first season would have aired on April 25, 2013—had the Boston Marathon bombings not taken place just 10 days before. It’s also worth noting that the memory of the Sandy Hook Elementary School shooting in December 2012 was still fresh in viewers’ minds. At creator Bryan Fuller’s request, NBC temporarily pulled the show from its lineup, slicing and dicing “Œuf” into five webisodes instead.

Star Trek: “Miri,” “Plato’s Stepchildren,” “The Empath” and “Whom Gods Destroy”

Despite the fervent protests of British Star Trek fans, “Miri,” “Plato’s Stepchildren,” “The Empath” and “Whom Gods Destroy” were banned from the U.K. airwaves for years. Why? According to the BBC, these episodes “deal most unpleasantly with the already unpleasant subjects of madness, torture, sadism and disease,” and they nixed them out of concern for the program’s younger viewers. To be fair, they’re not un-unpleasant. In “Miri,” for instance, Kirk and company come upon a planet inhabited by the children who will succumb to a terrible degenerative disease when they hit puberty. You know, just in case your kids weren’t having enough nightmares already.