James Gunn didn't "anticipate" bringing Clayface into the DC universe.

The 59-year-old filmmaker hadn't originally planned to include the horror story in his plans as DC Studios co-head, but the pitch for the film was too good to turn down.

He told Extra: "It wasn't something we anticipated building into the universe, but it was so good and so moving and so touching and unique that we knew we had to do it."

The movie features Tom Rhys Harries as Hollywood leading man Matt Hagen, who undergoes a cutting-edge treatment to restore his looks after being left horribly disfigured, but he begins to lose his grip on reality as a result.

And while a number of actors auditioned for the role, the White Lines star was a clear standout.

James said: "A lot of people auditioned for this role, but both me and Matt Reeves sort of fell immediately in love with Tom because he's got something that very few young actors do. He's a great actor. He's a good-looking guy, and he's just charismatic as hell."

Meanwhile, despite its horror premise, Tom believes Clayface is more of a "romantic film".

He said of the project: "The story and the script that I initially got was just so, like, arresting in and of itself and then to have the backdrop of DC and Batman and, you know, all of those elements.

"There's a lot of, like, goop and guts and gore, but I think the film in essence is a romantic film, I think, and Matt thinks he's in a different film than the one he is in. Hopefully, that gore is earned because it only really is effective if [you] care about the characters."

Mike Flanagan pitched the story and co-wrote the script for the film about one of Batman's most well-known adversaries, and he recently spoke of his disappointment that he'd not been able to take on directing duties because of his commitments to the next Exorcist film and the Carrie TV series.

Mike told Entertainment Weekly: "Between Carrie and The Exorcist, there was no way.

"I really wanted to do it, too. Though, when I was developing it, I thought it was going to be later in the DC rollout. I didn't think it would be the character they'd focus on so soon.

"But they were eager to get it into production and I wasn't anywhere near available. It wasn't 'Wait six months.' It was, 'No, I'm years away.' So I completely understand why they would want to do that."

Instead, James Watkins has taken the reins on Clayface and while Mike has only seen the trailers so far, he thinks he'll be pleased with the end result.

He said: "I haven't seen [Clayface] yet. That's James' movie. It looks like the movie I think it is.

"It's a weird situation because I turned in the script and it's like, 'James [Gunn], make your movie. I'm off to do my thing.' I've never been in this position before, but I'll probably see it when everybody else sees it."