Blue Devil, a comic which debuted in 1984, told the tale of Dan Cassidy, a stuntman and Special Effects expert who was part of the crew for a monster movie. He created an amazing, full-body prosthetic devil suit chock full of Practical Effects, and, since this was the DC Universe, a strength-enhancing exoskeleton, as well.
Naturally, it got worse.
Dan, of course, decided to fight off the demon in his souped-up rubber costume, and managed to drive it back into the aforementioned Can, and re-seal it. In the fight, alas, he took a full-on blast from the demon's Eye Beams — and when the dust cleared, he realized that he could no longer take the suit off. It was fused to him.
Because of this weird fusion of magic and technology, Dan became a Weirdness Magnet — in fact, this is the Trope Namer. His comic was a funny, fun-filled romp through the superhero universe, with tongue-in-cheek side trips into the territory later staked out by Vertigo. Dan even joined the Justice League, during the soap operatic and angst-heavy Gerard Jones run.
Since then he's become a member of a team title, Shadowpact, which has a team of magical troubleshooters including other "esoteric" DC heroes, which include Detective Chimp and Phantom Stranger, and has even joined the Justice Society of America. His sidekick, Kid Devil, suffered a similar fate (and later joined the Teen Titans).
In the New 52, Blue Devil co-stars with Black Lightning in a few issues of the Anthology Comic, DC Universe Presents. In the New 52, Dan Cassidy is once again a man in a blue skinned devil suit. However, the suit is now completely magical, as it is actually made from the skin of the demon Nebiros. The suit was given to him by his grandfather.
- Arch-Enemy: The demon Nebiros, until he was killed in Day of Judgment.
- Back from the Dead: After he becomes a proper demon, death becomes a temporary thing for him.
- Bare Your Midriff: A rare male example in the New 52. Blue Devil's costume shows off his chest and abs. At one point, he mentions having to keep his chest waxed.
- Becoming the Mask: A very literal case. After he sacrifices his life to stop Neron's plans, he comes back to life as an actual, factual demon. As a lifelong Catholic, Dan is less than pleased.
- The Big Guy: In Shadowpact.
- Blessed with Suck: Not least because he's a devout Roman Catholic who, because of his Deal with the Devil, can never again enter a church.
- Came Back Strong: Seemingly dies during Underworld Unleashed, but comes back as a full-fledged demon.
- Civvie Spandex: He has ditched his old costume for a black T-shirt and jeans since the 2000s.
- Dark Is Not Evil: He's (technically) a devil, but also a good guy.
- Deal with the Devil: During Underworld Unleashed, Dan made a deal with Neron—he could be a movie star, and all he had to do was destroy an abandoned power station in the middle of nowhere. Unfortunately, thanks to the lights it powered not being on, Dan's producer/agent/close friend Marla Bloom was killed in a helicopter crash. Calls and offers from sympathetic Hollywood folks began pouring in, but understandably he was in no mood to answer.
- Egocentric Team Naming: Annual #1 had several supernatural-themed characters team up. At the end, the Creeper suggests they be a regular team called "The Creeper's Spirit Squad". Which everyone thinks is "the stupidest idea I've ever heard!".
- Four-Fingered Hands: His costume in the New 52 has four fingers, but Dan can easily put his five fingers in them. Justified as the costume is magical.
- Genuine Devil Hide: His costume in the New 52. Dan thinks it's just a high tech suit until Black Lightning points out the wires inside are really veins. It's made from the demon Nebiros's skin, and the guy really wants it back.
- Holy Burns Evil: The Mist II temporarily kills him at one point by replacing the water in the sprinklers of the building he's in with holy water.
- Inappropriate Role Model: When confronted by Zauriel, he learns that as a demon and a superhero, BD's inadvertently making Hell look awesome and setting an example for weak people to sell their souls so they can be like him. This spurs him to try and get out of his infernal contract.
- Kid Sidekick: Eddie Bloomberg (Marla Bloom's nephew) was temporarily Blue's, though he later became Kid Devil/Red Devil and joined up with the Teen Titans during One Year Later.
- Magic from Technology: The suit before he was fused with it.
- Magitek: His original costume.
- My God, What Have I Done?: After Marla's death. Particularly when his sometime sidekick Kid/Red Devil also made a deal with Neron to get powers, with the condition that if he ever lost his faith in Dan, Neron would get his soul. One confession later...
- Rhymes on a Dime: At one point, he's demoted to a Rhyming Demon.
- Weirdness Magnet: The Trope Namer.
- Whole Costume Reference: Blue Devil's New 52 costume looks extremely similar to an unused design for Kid Devil drawn when he renamed himself Red Devil and got a new outfit.