LOS ANGELES — Watch out for the horse, cautioned Greg Nicotero.

It was a sweltering September morning at Universal Studios and inside a new maze based on “The Walking Dead,” the movie-makeup master and co-executive producer of the AMC series pointed to the floor where a zombified horse cadaver lay on its side, shrouded in plastic sheeting. Trap doors had been left conspicuously open and a few headless bodies had been strategically placed to give visitors the same sort of thrills they might experience in the post-apocalyptic American South of the hit zombie show, a nightmarish realm where flesh-eating ghouls hungrily devour their prey, equine or human.

“The Walking Dead: Dead Inside” maze is this year’s centerpiece for Universal’s Halloween Horror Nights, the annual event that transforms the theme park’s family-sun-and-fun ethos into something far more dark, grisly and adult in the weeks leading up to the spookiest day of the year. The event is also at the Orlando location.

“This is not a carnival attraction, this is not a haunted house that somebody’s having in a high school parking lot,” Nicotero said. “This is really about taking the participant and putting them inside the show.”

Few people understand and appreciate zombies the way Nicotero does, though that might be a simple accident of geography. The Pittsburgh native grew up watching monster movies in the same city where George Romero revolutionized and politicized the horror film with his radical 1968 zombie film “Night of the Living Dead.” Now 49, Nicotero began to learn his craft apprenticing with Tom Savini, Romero’s mustachioed makeup effects artist, the man widely considered the patron saint of splatter.

Since he turned professional in the mid-’80s, Nicotero has worked with Sam Raimi, Frank Darabont, Robert Rodriguez and Quentin Tarantino on horror films and more commercial movie and TV projects. He’s won four Emmys and his credits include HBO’s World War II miniseries “The Pacific.”

But there’s no question his heart belongs to horror. The first film he recalls seeing is 1966’s “Dracula: Prince of Darkness,” starring Christopher Lee, which was released when Nicotero was 3. His vast knowledge of the genre not only influences his speech, which is littered with enough references to fill a cult movie guide, but also it affects what “Walking Dead” viewers see from week to week. (The show returns for its third season Oct. 14.)

On the series’ Georgia set, he runs a “zombie school” for extras who play the feral walkers, personally demonstrating how they should move and at what speed. He points out that walkers rarely wear clothing that would telegraph the people they had once been — lab coats, uniforms and the like.

“When an audience starts identifying them as caricatures they become less threatening,” Nicotero said, sounding a little like an ambassador for the monsters. “What we have successfully been able to do is take these characters and make them simultaneously scary, creepy, sympathetic, threatening so that you get a sense that these people were actual people.”

John Murdy, Halloween Horror Nights’ bespectacled creative director, himself a lifelong genre fan, shares Nicotero’s enthusiasm for the undead. It was one of the reasons he was keen to include “The Walking Dead” in Universal Studios’ horror lineup — in addition to the maze itself, the theme park has created a “Walking Dead”-themed “terror tram,” which will drop visitors off on the back lot where they’ll have to make their way through roughly 125 actors dressed as zombies.

Halloween Horror Nights is one of a handful of similarly scary Southern California events — Knott’s Berry Farm, Six Flags and Disneyland all offer their own take on the holiday — though Universal Studios prides itself on big-name entertainment tie-ins. Affiliation with the movie studio is optional.

Previous Halloween Horror Nights have featured mazes designed around horror movie franchises including “Friday the 13th,” “A Nightmare on Elm Street” and “Saw.” This year, Halloween Horror will bolster its brand of bloody mayhem with haunted attractions based on the video game/movie franchise “Silent Hill,” “The Texas Chainsaw Massacre” and the studio’s own classic monsters.

“We want to feature properties people know and love,” Murdy said.