When Joe Gilgun got the call telling him he was being courted to play Irish vampire Cassidy in AMC’s adaptation of “Preacher," he had never read the cult classic Garth Ennis comic and had little interest in playing a vampire. “I don’t want to be a sexy vampire. I’m f------ sick of them,” he remembers thinking.

But Gilgun, who is best known for the British TV series “Misfits,” was a fan of the prospective show’s executive producers, comedian Seth Rogen and Rogen’s longtime writing partner Evan Goldberg. He soon signed on to play the part (which is a vampire, though far from sexy), but not without reservations about the comedic pair’s ability to write, direct and produce the dark material.

“I didn’t think they were capable,” Gilgun told International Business Times. “I thought we were all f-----.”

Indeed, Rogen, who made his name with farcical cinematic comedies like “Superbad” and “This Is the End,” would not have seemed the most likely choice to adapt the decidedly grim “Preacher.” But after nearly two decades of failed attempts from other filmmakers, including Oscar-winner Sam Mendes and comic superfan Kevin Smith, the comedian is the one bringing the comic to the screen. Ultimately, Rogen’s comedic background was the key to finally getting the series off the ground.

“I think because [‘Preacher’] was funny was the thing that made [Goldberg and I] think we could do it,” Rogen told reporters Thursday. “As we looked at other versions of it crumbling from afar, it seemed to be the one thing that was missing. Comedy is the easiest thing to ignore and it’s the easiest thing to marginalize. So, I can see why in trying to adapt “Preacher,” it would be the first thing to think it’s not important.”

“Preacher,” which premieres Sunday, tells the story of Jesse Custer (Dominic Cooper), a criminal-turned-preacher in a small Texas town who becomes possessed by a mysterious spiritual entity that gives him supernatural powers. Jesse eventually teams up with Cassidy and his ex-girlfriend Tulip (Ruth Negga) to fend off enemies from heaven and hell — literally — who want his new powers. Though the series deals in some heavy subject matter — violence, morality, religion — it often breaks the tension with many comedic elements, including slapstick humor and some well-placed pop culture references. That’s where Rogen comes in.

“People think [comedy is] easy and people think it’s not as important as these other things: drama, romance, religion. ‘Anyone can do comedy.’ I think that’s what makes the comic different and that’s what makes the show different, and not just this brooding thing,” said Rogen. “It has so many styles and tones and is always undercutting its own ideas with these weird ideas."

Since soon after Ennis’ comic came out, in 1995, filmmakers have been eyeing the books as a possible show or movie. But like other admired graphic narratives before it, such as Alan Moore’s “Watchmen,” the many characters, conflicting tones and controversial storylines in “Preacher” proved difficult obstacles to getting a green light from any major studio or network. In the early 2000s, notable directors like Mendes and, later, Smith and D.J. Caruso, took a stab at it. Rogen was even in correspondence with Mendes in pursuit of the role of Eugene (aka Arseface). But nothing ever materialized.

“The other problem was I could not find a way of making ‘Preacher,’ ” Mendes told Collider in 2012. “Tonally it’s a very difficult thing to make work, and there’s a reason why it has struggled so much. It’s a brilliant graphic novel, I loved it, but a lot of it takes place in the real world, and we’re surrounded now by fantasy and superhero genre pictures, which are full of eye candy. ‘Preacher’ is much more real world. It’s more of a Southern Gothic with elements of the fantastic in it. It’s a quite difficult thing to balance. So it wasn’t just that I sort of walked away from it because they wouldn’t pay for it or anything like that, it was because I couldn’t really make it work. I couldn’t find a way of defining what it was onscreen. My strong suspicion is someone will come along who has a really good take on it and is able to do it.”

A few years later, following the success of multiple comic book adaptations on the small screen, most notably AMC’s “The Walking Dead,” Rogen did come along with a vastly different take. In the books, Jesse and his friends set out on the road to track down the source of his powers. But in the AMC show, the trio stick around town much longer, basically turning the first season into a prequel to the comics. Rogen has also introduced some new elements to the universe.

“The comics aren’t very mysterious,” Rogen said. “We were really influenced by shows like ‘Lost.’ There was nothing more fun than getting together with my friends watching that show and trying to guess what was happening and who’s that guy and why are they connected. That is something we made more a part of the show because we love shows like that.”

Photo: AMC

Rogen was also in complete creative control on set, winning over his early skeptics.

“[Seth and Evan] make incredible directors,” Gilgun said. “I thought they were just a pair of stoners and there would be some d---head there doing all the shots for them and they would be like, ‘do it like this’ and ‘say like it this,’ like sort of creative directors. But they knew everything. They did every shot. They knew how much time they had, they knew when they were running down — it was impressive to watch.”

Perhaps it should not come as such a surprise that Rogen is able to balance multiple, seemingly contradictory tones. His comedies have always incorporated genre mashups — “The Interview” is also an action movie; “This is the End” is also a horror film.

The proof of Rogen’s success appears to be in the pudding. “Preacher” has an 89 percent rating on review aggregate site Rotten Tomatoes, signifying near-universal acclaim. Perhaps the material just needed a comic’s eye all along.

"Preacher" premieres on AMC at 10 p.m. EDT Sunday. Watch the trailer below: