This Is How ‘Simpsons‘ Writers Make a ‘Treehouse of Horror’ Episode

Thirty-two-year-old Julia Prescott feels like she never really knew a world without The Simpsons. From the moment she first saw the show — at around age 5 — there was an undeniable appeal. “It had that, Whoa, they’re talking to ME! blend of physical comedy, perfectly structured jokes and the James L. Brooks touch of bringing us back to the heart of the story in a way that always felt earned,” she tells me. 

As a child of divorce, it was also something that bonded her with her dad. “I only got to see my dad on the weekends, and he made a VHS tape of favorite episodes from Seasons One and Two that I would wear out over time,” she says.

Her love of the show carried into adulthood, which is when she met Allie Goertz, another Simpsons superfan. Together, they created the podcast Round Springfield, where they interview writers and performers who have worked on the show. Prescott never dared to dream that she would write for the show herself, but after a few people encouraged her to send in an application packet, she was overjoyed to be hired. Making it all the better? Her first episode would be this year’s “Treehouse of Horror,” The Simpsons’ annual Halloween episode.

She couldn’t believe her luck. “Who ISN’T a fan of the ‘Treehouses’??? I mean, they’re the freakin’ ‘TREEHOUSES’!” she exclaims, still in disbelief. “And holiday episodes of any TV show are always incredibly fun, an annual tradition that breaks canon and just goes to crazy town.”

The “Treehouse of Horror” episodes began in the show’s first full season (technically Season Two), with the original airing on October 25, 1990. Jay Kogen wrote one of the segments, along with Wallace Wolodarsky. “Matt Groening had an idea for an episode where the kids tell ghost stories in a tree house,” Kogen explains. “It wasn’t met with much excitement, but my partner Wally and I championed it over and over until Sam Simon, the showrunner, finally agreed. For Matt, the idea was kids telling stories. Sam decided it should be more about the archness of the stories themselves. It gave us a chance to be even weirder and break out of the sitcom form we were in most of the time. It was meant as a one-off, but it was so much fun we did it again the next year and it became a tradition.”

The segment Kogen wrote was a parody of the iconic Twilight Zone episode “To Serve Man,” where aliens come down and solve Earth’s problems just to make a farm out of our planet so they can eat humans. His favorite bit was a play on the big reveal in the original. “When they discovered the [cook]book, it kept changing its meaning when they dusted off more of the title,” he says. “It goes from How to Cook Humans to How to Cook for Humans to How to Cook Forty Humans to How to Cook for Forty Humans.”

But Kogen’s biggest contribution was probably the creation of Kang and Kodos, the two aliens who have made appearances in every “Treehouse” episode since. “I actually drew them myself,” he tells me. “They’re the only thing I ever drew for the show.”

Despite the fact that it was supposed to be a one-off, the multi-segment structure established in that first “Treehouse” episode is considered to be set in stone by the writers. Per Bill Oakley — who wrote a “Treehouse” segment in addition to producing/showrunning a couple full such episodes with his partner Josh Weinstein in the 1990s — the process goes like this: “There would be a warning or wraparound up front (though as the episodes got longer these sometimes got cut for time) and three one-act segments. The other traditions were obviously everyone having a funny Halloween name in the credits, and for a time, there was a thing with funny tombstones in the opening. But again, these ended up getting cut for time when we were running the show. Plus, the tombstones were notoriously hard to come up with.”

Everything else, Oakley says, was fair game. “You were allowed to go WAY outside the bounds of what we normally were allowed to do — both in terms of gore and scares but also in terms of being faithful to the characters and relationship status quo in Springfield.”

To that end, in “Treehouse of Horror VI,” Oakley got the idea to send Homer into another dimension. The segments used an innovative 3D computer animation that was considered groundbreaking at the time. 

Like Prescott, current Simpsons writer/producer Tim Long’s first experience working on the show was pitching a segment for a “Treehouse” episode back in 1999. ”It was odd, but I realized that we’d never done a superhero-themed segment — and also that we’d never done anything where the kids actually went out trick-or-treating. After I realized there were those two holes left to fill, the idea just sort of came together.”

Long’s segment was called “Desperately Xeeking Xena,” and it featured big-time guest star Lucy Lawless. “She had a fairly heartfelt speech about how she felt awkward growing up as a big, athletic girl in New Zealand, just before it turned out she was tricking Comic Book Guy into letting his guard down. She really leaned into that.” (There was also a bit of trauma from Long’s own childhood in the segment: When it begins, Milhouse is wearing a plastic smock with the name Radioactive Man on it, which Long says was inspired by his own mom. “I asked my mom for a Batman costume one year,” he tells me. “And I got a smock that said ‘Batman.’ It was very dispiriting.”

The segment also contains one of Long’s all-time favorite lines: “When she whispers to Comic Book Guy, ‘Xena needs xex.’ There are very few lines that you can be 100 percent sure have only been uttered once in TV history, but ‘Xena needs xex’ is surely one of them.”

While the “Treehouse” episodes take on themes related to the supernatural and science-fiction, horror is the primary focus, and writers are encouraged to make things as terrifying as possible. And so, there are definitely some chills with all that laughter. Prescott easily names two segments that left her frightened: the gremlin on the schoolbus from “Treehouse of Horror IV” and a Freddy Kreuger-esque Groundskeeper Willie from “Treehouse of Horror VI.” Moreover, she says, “The off-model looks of any of these characters are always unsettling to me. I also think the fact that these segments have to move so fast storywise that there’s not enough time to really let the scary elements breeze, making them even scarier. Within two minutes, we’re already facing some demon haunting these characters we know and love — it’s terrifying!”

“I know the Groundskeeper Willie as Freddy Kruger segment did indeed scare a lot of people — mainly kids who hadn’t seen Nightmare on Elm Street,” Oakley adds. “Because even to this day, someone tells me about once a month how that segment scared the shit out of them as a kid and how they had bad dreams about it. In retrospect, I don’t think I would have toned it down, but I do feel a bit bad about terrorizing all those children.”

For his part, Long is surprised at how influential all the “Treehouse” episodes have become, as evidenced by a tweet about one of his favorite Treehouse moments last year. 

The line in question is from “Treehouse of Horror XIX” and involves legendary actor Rip Taylor. After the tweet took off, Long got a nice surprise — The New York Times embedded the thread in their obit for Taylor. “A lot of the excitement around these episodes isn’t just the fact that it’s Halloween, but that there’s this electric element of surprise like, ‘What are they gonna do this year? How are they gonna surprise and delight us?’” Prescott says. “In some ways, it feels like sitting around the campfire on the first night of camp and waiting for the skits to start. You’re basking in the glow of your friends and this thing that you love, and you’re excited to see how they’ll raise the bar or change things up.”

And now her stories will be a part of that “Treehouse” legend. “I hope I deliver on that front both as a fan and a writer,” she says. “And if people don’t like it, I’ll be muting my Twitter replies!”

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Desi Jedeikin

Desi Jedeikin is a writer living in Los Angeles. She co-hosts the podcast Hollywood Crime Scene and has lots of things in development that will probably never happen. She wastes a lot of time on Twitter @desijed.