Preacher to the converted

For more than 20 years, Garth Ennis has been tackling subjects such as his native Northern Ireland, religion, the second World War and the problem with superheroes. Although the likes of Sam Mendes and HBO have come calling to do screen adaptations, he tells LIAM BURKEthat he's happy being Holywood's second most famous export

DRESSED IN A BLACK SUIT and Dr Martens boots, Garth Ennis strides in under a dangling second World War Spitfire before stopping by a V-2 rocket to sign one of his books for a fan. Ennis should be feted as an important Irish writer. He has spent more than 20 years at the top of his field, has an international fan base that includes A-list directors such as Sam Mendes and, here, is a guest of honour at the Imperial War Museum in London. Perhaps that the Co Down author is not widely known is attributable to his chosen medium: comic books.

The 41-year-old has picked up more industry awards than any mantelpiece can reasonably hold by deftly mixing black humour and incisive commentary in some of the most celebrated and controversial comics of the past two decades, including the Northern Ireland-set coming-of-age drama Troubled Souls, the supernatural Western Preacherand the superhero satire The Boys. This is in addition to runs on the comic-book icons Judge Dredd, Batman and the Punisher. But it is his love of war comics that has formed the backbone of Ennis's career – and that has lured him from his New York home to last weekend's Comics and Conflict conference at the war museum.

The first thing that strikes you about Ennis is his candour, as he returns matter-of-fact responses in a measured northern accent that has been only slightly softened by a decade in the US. For instance, when asked why, as a 19-year-old, he chose the sectarian conflict of his surroundings as the subject of Troubled Souls, his first foray into comics, he does not allude to childhood traumas. "I grew up in a quiet little town [Holywood] outside Belfast. So I have no horror stories to tell," he says simply.

"It was the kind of thing that was doing well at the time. I ought to be completely clear and say that, with hindsight, what Troubled Soulsreally represented was naked ambition. It was a direct attempt to get published. And that was the road that seemed most likely to lead me to success."

Ennis is selling himself short. Troubled Souls, written in 1989, challenged the cliches of Northern Irish narratives and remains a thorough engagement with the Troubles in a media landscape mired by apolitical simplification.

Ennis's modern-day antipathy to his reputation-making book notwithstanding, Troubled Soulsclearly had the desired effect, propelling the ambitious writer to British comic 2000 ADand its most famous character, Judge Dredd, where he continued his interest in Irish topics while also building an international reputation. One story even found Ennis sending Judge Dredd to the Emerald Isle (formerly known as Ireland), a theme park based on Irish stereotypes – imagine Temple Bar writ large.

In critiquing the part the Irish play in perpetuating the stereotypes we so often bemoan, Ennis would display the confrontational, politically engaged style that would later mark his most celebrated work, Preacher. First published by DC Comics's mature imprint Vertigo in 1995, Preacheris a modern-day Western following Jesse Custer, a possessed US Southern reverend, who is literally looking for God after the Almighty has shirked his responsibilities and fled to Earth. Ennis, an atheist, is typically direct about the book: "It's blasphemy."

It would be easy to dismiss Preacheras a controversy-baiting career move were the book not so richly detailed and the story so involving. During the five years Preacherwas published, Ennis picked up many plaudits. "Neither Steve Dillon [its artist] nor I could have known it, but it really did put us both up a level; it got us to a place in the business through notoriety, or whatever you want to call it, that made us hard to forget."

Everyone from Mendes to HBO was eager to adapt his mammoth work, but even after 15 years, as Ennis says, “We’re really no closer than we ever were.” He cites two factors for his fan favourite stalling at the planning stage. “One is that there are nearly 2,000 pages and the structure of it is such that it’s very hard to isolate a small fraction to do as a story for a film. The other reason is the religious aspect, because no one has ever said, ‘Yes, God exists, but he’s a dick.’ ”

ENNIS'S PRAGMATIC ATTITUDE gives him distance from the film-production merry-go-round, which he dismisses as "black magic". He describes his involvement as "almost nil", explaining, "It really doesn't make much sense to pour your heart into something you have no control over and you might never see a cent for." Indeed, Ennis isn't waiting on the studios. He recently wrote and directed a short film, Stitched. He was driven to make the move to film to "see if I could do it"; Stitched(unsurprisingly, a war story) premiered at this year's San Diego Comic-Con. Reflecting on the change of medium, Ennis says it was "very hard work, but hugely enjoyable".

Despite Preacher's crawl towards the screen, Ennis believes his superhero satire The Boysis closer to filming, "I think it would be quite simple to take those five characters and say, 'These guys beat up superheroes.' With all the superhero movies out at the moment, half your battles are already won."

The Boysgrew out of his disdain for the superhero genre, the US comic-book industry's dominant style. The writer says that reading late-1970s British war comics such as Charley's War, Johnny Redand Commandowas a formative experience, and he didn't read superhero books until his late teens, at which point he found them ridiculous. As a student of history he considers second World War superheroes such as Captain America "borderline offensive, because to me the reality of World War II was very human people, ordinary flesh-and-blood guys who slogged it out in miserable, flooded foxholes. So adding some fantasy superhero narrative, that has always annoyed me a little bit."

Ennis has stuck to more grounded comic-book stock, such as a CIA operative, Nick Fury, and a Vietnam vet, the Punisher. He has even managed to use his mainstream success to resurrect the war comic with titles such as War Stories, Battlefieldsand Adventures in the Rifle Brigade, stories that allow him to dip into his historical knowledge – while we talk he tells anecdotes about the weapons on show at the Imperial War Museum – while dulling none of his subversive streak.

ENNIS IS AWARE of the price to be paid for his publishers indulging him in a waning genre. "You earn your brownie points and you spend them as you can." To earn more brownie points, Ennis occasionally must return to spandex and capes – but he seizes the opportunity to subvert these styles. When an early issue of his DC Comics title Hitmanfeatured Batman, Ennis punctuated the pomposity of the Dark Knight by having his profane protagonist, Tommy Monaghan, vomit on the Caped Crusader's boots – biff, pow, splatt!

As Tommy Monaghan's surname suggests, Ennis has maintained an Irish inflection in his work. "I think it's just occasionally returning to what interests me." One such opportunity came with Cassidy, the Irish vampire of Preacherwhose origins Ennis tied into the Easter Rising. "It gives the character extremely Irish credentials. Yet at the same time he gains a vein of cynicism and he's happy enough to leave Ireland behind and go to America and make his fortune there."

It is hard not to see a parallel with Ennis’s experience. Six months ago he was sworn in as a US citizen, motivated to make the move by “getting the sensation straight away that you are supposed to be here; this is what your life was aimed at. That’s how I felt about New York in particular and America in general.”

Nonetheless, he makes it home several times a year, and if he is not quite as recognisable as one golf-club-wielding Holywood native, Ennis doesn’t mind. “I don’t really do it for praise. My stuff sells well and I make a comfortable living off it. I’m happily anonymous.”

The best of Garth Ennis

Troubled Souls Less explicit than Ennis's later work but no less polemic, Troubled Souls subverts the conventions of representing Northern Ireland.

Judge Dredd, Emerald IsleJudge Dredd heads to the Emerald Isle (formerly Ireland), where he teams up with the hard-drinking Judge Joyce. Broad comedy and incisive commentary mix in this play on Irish stereotypes.

Hellblazer In this comic, based on the Alan Moore-created character John Constantine, Ennis introduced an Irish love interest, Kit Ryan, for the occult detective. Ennis's Dangerous Habits story arc would be the basis for the 2005 Keanu Reeves film Constantine.

Hitman Tommy Monaghan is a hard-drinking Gotham City-based Irish-American hit man with superpowers who once attempted to join the Justice League so he could try his X-ray vision on Wonder Woman. Irreverent fun.

Preacher Ennis's most celebrated work is a 66-issue trek across the US literally to find God, with a possessed reverend, an assassin named Tulip and a hard-drinking Irish vampire. (There's a trend forming here.)

The Punisher, MaxEnnis revived the long-running Marvel Comics vigilante with two distinct takes: a Looney Tunes phase and a more realistic post-9/11 version, which generated enough interest to prompt two (lacklustre) film adaptations.

The Boys CIA operatives the Boys are tasked with keeping the amoral and narcissistic superheroes of the world in line. This unashamedly profane superhero satire has divided Ennis fans.

War Stories This anthology of collaborations with some of the comic industry's finest artists finds Ennis telling a number of second World War stories from differing front-line perspectives.