For the uninitiated - Hellblazer is a horror comic about John Constantine, trenchcoated modern-day wizard antihero, confronting supernatural/magical unpleasatness in a modern setting. He was created during Alan Moore's Swamp Thing stories, before spinning off into own series after fans enjoyed his manipulative schemes and wry British comments.
Hellblazer distinguished itself from other urban fantasy via particular emphasis on straight-up awful horrific moments and a tendency to reference real modern-day British issues rather than just the affairs of its own fictional universe, all of which made it a massive cult hit.