He later used this experience in his comic book series, Preacher, whose protagonist is slapped after telling his grandmother that he finds the concept of God "scary".

[4] Ennis began his comic-writing career on his nineteenth birthday in 1989, with the series Troubled Souls in the British anthology Crisis.

[5] Illustrated by Ennis's friend John McCrea, as living in Northern Ireland meant he did not require reference material for the Belfast-based series, it tells the story of a young, apolitical Protestant man caught up by fate in the violence of the Irish Troubles.

After publicly insulting his classmates' religion to get back at a girl he was interested in who did not return his romantic feelings, the boy attracts the attention of a maltheist and is coerced into helping him murder clergy and bomb churches.

[8] Shortly after, Ennis began to write for the UK comics series 2000 AD, and later wrote stories for the title's flagship character, Judge Dredd, taking over from creator John Wagner for several years.

In 2001, following much work in the United States, Ennis briefly returned to UK comics to write the Judge Dredd story "Helter Skelter".

Years afterward, Ennis briefly returned to Hellblazer for the five-part "Son of Man" story with artist John Higgins.

No longer finding violence comedic in light of the September 11th terrorist attacks, Ennis relaunched The Punisher under Marvel's MAX imprint, allowing for darker stories.

[9][12] In 2008, Ennis ended his five-year run on the MAX imprint's Punisher series to write the Marvel miniseries War Is Hell: The First Flight of the Phantom Eagle.

These stories stripped superspy Fury of his science-fiction trappings in favor of military and CIA situations, including a focus on the First Indochina War in one storyline.

Avatar has published the bulk of Ennis's creator-owned material, which includes the post-9/11 war story 303, a western entitled Streets of Glory,[17] the extreme horror comic Crossed,[18][19] Back to Brooklyn, a crime limited series co-written with Jimmy Palmiotti for Image Comics,[20] Caliban, a science fiction horror series inspired by the movie Prometheus,[21] and Chronicles of Wormwood, which dealt with the friendship between an African-American Jesus Christ and a benign Antichrist.

In 2011, Avatar commissioned Ennis to write and direct an original short film, Stitched, produced to drum up support for a possible feature.

Mainly illustrated by co-creator Darick Robertson, who Ennis previously worked with on the Marvel series Fury: Peacemaker and Punisher: Born, The Boys ran for 72 issues before concluding in 2012.

[34] Ennis wrote Sara in October 2018 for TKO Studios, a war story following a team of female Russian snipers as they beat back the Nazi invaders during a brutal winter campaign on the WWII Eastern Front.

[39] Ennis said he was "blown away" by Miller, as The Dark Knight Returns was the first time he encountered a comic writer who approached his work like a novelist.

"[6] Nonetheless, Ennis has admitted to having appreciation for the idea behind Wonder Woman if not the character, and even to outright liking Superman, the latter of whom he was noted for writing respectfully in Hitman.

"Which is not to say I don't think there's potential for the genre – Alan Moore and Warren Ellis have both done interesting work with the notion of what it might be like to be and think beyond human, see Miracleman, Watchmen and Supergod.

But so long as the industry is geared towards fulfilling audience demand – ie, for the same brightly coloured characters doing the same thing forever – you're never going to see any real growth.

"[42] Ennis has remarked that in terms of Marvel and DC characters, he prefers the ones he describes as more grounded, such as the Punisher, John Constantine, and Nick Fury.

He told Vulture in 2014 that he had come to find Constantine morally repulsive and had "no desire to write a character who essentially gets his pals killed and then explains that they were doomed anyway, so why not just spend their lives and use them up.

Ennis has related that having been raised secular, religiously motivated violence made no sense as to him, characterizing such conflict as a disagreement among participants over "how to worship their imaginary friend.