Blue Devil (Dan Cassidy) first appeared in a special insert published in Fury of Firestorm #24 (June 1984). That story led directly into Blue Devil #1, also cover dated June 1984. He was created by Dan Mishkin, Gary Cohn, and Paris Cullins. The Blue Devil comic book ran for 32 issues with Blue Devil later appearing as a regular character in Shadowpact that ran for 25 issues.
Dan Cassidy was working as a stuntman and special effects specialist in Hollywood when he created the Blue Devil full body suit, complete with a built in exoskeleton, specifically designed for the Blue Devil movie being produced by Verner Brothers Studios.
During filming on The Blue Devil, the demon Nebiros was accidentally unleashed from within an ancient temple and, thinking Cassidy was an actual demon, tried to drain his demonic powers with blasts of magic. Instead, the blasts permanently bonded the suit to Cassidy. This unnatural fusion of magic and technology caused Cassidy to experience unusual events and draw the attention of otherworldly beings, a condition known in occult circles as a “weirdness magnet”.
EHT Comics 