He has also done work in the Top Cow/Marc Silvestri title "The Darkness" and written many limited series like "Fury" covering Marvel's Nick Fury character, Thor: The Vikings, and more recently Ghost Rider: Trail of Tears.

The subject matter of his work is usually of a adult nature, containing extensive violence, profanity, and dark humor. Ennis' writer-owned title, "The Boys," was pulled by Wildstorm (a division of DC) after 6 issues due to its graphic content. The title has now resumed publication by Dynamite Entertainment, including the release of a trade paperback containing the 1st 6 issues.

Ennis also currently writes Seven Brothers, a comic under the "Director's Cut" series of the young, India-based Virgin label. John Woo created the story, but Ennis continues to script the comic.