The Batman Comic Book Easter Egg In It: Welcome To Derry, Explained

Stephen King's novel "IT" was published in 1986, so the story's "present day" was the 1980s and the 27-years-ago past was the late 1950s (i.e. when King himself was the age of the Losers' Club). The "IT" films, directed by Andy Muschietti, moved the two eras decades up; now the past timeline took place in 1988-89, while the modern day was the contemporary 2010s.

Since Pennywise (Bill Skarsgård) only awakens every 27 years, the new prequel TV series "It: Welcome to Derry" is set in 1962. To add some period flavor, the pilot episode shows that Teddy Uris (Mikkal Karim-Fidler) owns two DC comics of the era. (HBO and DC have the same parent company: Warner Bros. Discovery.)

One is 1961's "Detective Comics" #298, the first appearance of Matt Hagen, the second Clayface. Next year, the villain will be the focus of director James Watkins' "Clayface" movie, as played by Tom Rhys Harries, but he was really a film star before that.

The original Clayface, real name Basil Karlo, debuted in 1940's "Detective Comics" #40. He was a murderous actor who adopted the costume and name of a character he'd played in a horror film. (Note how Karlo's name is meant to sound like Boris Karloff, who was most famous for playing Frankenstein's Monster.)

Hagen's creators, Bill Finger and Sheldon Moldoff, revived the "Clayface" moniker with a more intuitive meaning: he was a man transformed into amorphous, shapeshifting clay. "Batman: The Animated Series," and reportedly 2026's "Clayface," used the Hagen Clayface but with Karlo's actor backstory.

Is this Clayface cameo just to tease the movie? Though the Batman villain who Pennywise most obviously resembles is the Joker, remember that the Dancing Clown is also a shapeshifter like Clayface. Thus, Teddy gets a taste of the horror ahead of him.

The other comic shown in "Welcome to Derry" is one that went on to be absolutely pivotal to DC history: 1961's "The Flash" #123 or "Flash of Two Worlds!" Created by writer Gardner Fox and artist Harry Lampert in 1940, the original Flash's secret identity was Jay Garrick. The Flash disappeared from comics in 1951 as the first superhero boom subsided. Then, in 1956, writer Robert Kanigher and artist Carmine Infantino revived the Flash. The new Flash, named Barry Allen, had similar traits (super-speed powers, a red lightning-themed costume), but he was a distinctly different character than Garrick.

In "Flash of Two World!", Fox got to tie his Flash to the new one. Barry Allen is transported to an alternate universe and discovers a different Flash: Garrick. All the "Golden Age of Comics" DC heroes who had faded away in the '50s had existed alongside Garrick in this world, dubbed "Earth-Two." For better or worse, this single story became the basis of the entire DC multiverse.

Why is this comic in "Welcome to Derry," though? Probably because the series pilot was directed by Muschietti. After the "IT" films, he directed 2023's "The Flash." That movie has a similar hook as "Flash of Two Worlds," as it centers on both Barry Allen (Ezra Miller) and a version of himself from an alternate timeline (also Miller).

"The Flash" was quite the bomb, but Muschietti still defends it. Apparently, he's proud enough of "The Flash" to pay homage to the titular character in his other work.

"It: Welcome to Derry" airs on HBO and is streaming on HBO Max. New episodes release on Sundays at 9 p.m. EST.