The coolest haunted house in Montgomery County might be in the yard of a suburban Kensington home.

Every year since 2014, Holly Agouridis has transformed her single-family house at 11423 Catalina Terrace into the Catalina Haunt. During the month of October, the insurance adjuster by day and haunted house designer by night invited a headless horseman, anthropomorphic tarantulas, towering zombies and possessed scarecrows to hang out on her lawn and entertain guests.

It started with just a few Halloween animatronics.

“A friend of mine came up to me one day, and she was like, ‘Hey, have you ever been to the store called Spirit Halloween?’ I thought all the moving animatronics were so cool,” Agouridis said.

So she bought a few at a steep discount on clearance after Halloween that year.

The rest is history.

In the past decade, the scene has become a cult favorite and family tradition for neighborhood residents and Halloween fanatics across the county. Today, Agouridis estimates that there are between 150 and 175 animatronics and props in her collection.

Every October, Agouridis’ suburban yard becomes a graveyard and a cornfield. Skeletons and talking pumpkins scatter the lawn, while ghouls and goblins of all persuasions talk to — and creep out — visitors. The porch is transformed into a twisted butcher shop, and a haunted baby doll crawls across the driveway.

“It’s completely terrifying, but I love it,” Gabriela Bodeya, 20, said while visiting the haunt on Thursday evening. “It’s so scary you can’t stop looking at it.”

Bodeya, who lives in the neighborhood, is one of the haunt’s dedicated fans. She’s been coming for more than three years, and introduced a friend to the attraction. They’d been considering visiting a professional haunted house together, but the Catalina Haunt may have been spooky enough for 20-year-old Maria Safronova.

“It is amazing how they put so much effort into this,” Safronova said. “I don’t know if I want to go to a haunted house now — this is creepy enough.”

The haunt delights and terrifies younger Halloween fans as well. Last week, 3-year-old Maggie Macneill of North Bethesda was too scared at first to approach the yard, but by the end of her family’s visit she was petting and high-fiving the animatronics. Maggie even tried to escape her father’s grasp when it was time to leave because she wanted to stay and explore.

Her parents started visiting the haunt with her 6-year-old brother Charlie when he was just a baby.

Gretchen Macneill, Maggie’s mother, said the family has installed a few animatronics of their own, with advice from Agouridis.

“We’ve really upped our ante,” Macneill said. “I’ve learned there is this whole subculture of people and Facebook groups talking about Halloween decorations.”

And what is the secret to making a yard display look like a professional haunted maze? Agouridis spends the day after Halloween scouring Lowe’s, Home Depot and Spirit Halloween stores across the county for markdowns on animatronics. She’s even enlisted coworkers to help search.

Her newest addition is the “Worricrow,” a 15-foot-tall crow and scarecrow hybrid that looks down over the yard.

“I have some kids who come here four or five times a week, and every year, they know what’s new,” Agouridis said. “It’s just amazing how these kids remember and notice everything.”

Setup takes time. Agouridis’ husband and two sons help her haul the decorations from their shed to the yard before Labor Day each year. She does all the setup, spending every weekend and evening after work getting the display ready to go until opening day on October 1. Her family helps her pack it all up again in the shed after the holiday is over on Nov. 1.

The question Agouridis is asked the most: How much damage does this do to her October electric bill? Perhaps surprisingly, Agouridis said she doesn’t see much of a difference from her normal bill. She chalks this up to the limited hours the display is open — around 6:30 p.m or sundown until 8 p.m., Wednesday through Sunday, from Oct. 1 until Nov. 1.

She spends an estimated $200 on batteries per season, and will accept donations if asked — but doesn’t expect them.

“I just want to create a safe and fun space for the community,” Agouridis said. “I love doing this and seeing all the reactions.”

In that regard, Agouridis’ mission may be successful.

“I really think more people should do community-building things like this,” Bodeya said. “I love how we all get to hang out as a neighborhood and have fun and be kids once again.”

Just don’t expect Agouridis to replicate her efforts at Christmas. While many visitors have asked her to consider a winter holiday display, the Catalina Haunt takes up her whole year — and decorating energy.

“After all this gets put away, I’m just happy when I get the tree put up and decorated,” she said with a laugh.