Horror directors seem to be a proving ground for DC's recent superhero movies, so it is perhaps no surprise that Mike Flanagan, who made The Haunting of Bly Manor as well as Gerald's Game and Doctor Sleep, has put a little thought into what he might bring to the DC Films universe if asked. Flanagan revealed on Twitter over the weekend that he had two main DC ideas already percolating -- one for a hero movie and one for a villain movie. There is no indication that he is being eyed for a DC property, but either (or both) is certainly fun to think about.
Zack Snyder jumped on board Man of Steel, he had done Dawn of the Dead. Movies like Shazam! and Aquaman recruited filmmakers with much more recent horror bona fides (namely David F. Sandberg of Annabelle: Creation and James Wan of Saw and The Conjuring, respectively).
"I've wanted to do a Superman movie since I was a kid," Flanagan admitted on Twitter. "But I would also be really keen to do a standalone Clayface movie as a horror/thriller/tragedy."
Clayface is a Batman villain (or rather, several Batman villains) that has a clay-like body and shape-shifting powers. Most versions of the character have some tragedy baked into their origin story, and during James Tynion IV's run on Detective Comics, he dug down into that a bit, with Clayface reforming and becoming part of Batman's team for a while.
Basil Karlo, the original Clayface, had no actual powers but was an actor-turned-serial killer who wore the "Clayface" costume he had worn for a movie. He learned that the studio was remaking one of his films without him, and dressed up to murder the movie's cast in the order they died in the movie (think Wes Craven's New Nightmare, but with Batman). In later stories, he would get powers, and at one point actually formed a team made up of all of the then-surviving Clayfaces to go after Batman together (which isn't a bad plan considering how powerful Clayfaces can be on their own).
As with so many other disfigured villains, later writers have explored stories where a few of the Clayfaces have had to grapple with what their monstrous new form has done to their personal lives, and whether the powers they got are worth it. That's likely what Flanagan alluded to in his tweet.
Karlo appeared on Gotham, played by Brian McManamon. Alan Tudyk is currently voicing Clayface on Harley Quinn.