OK, Hellboy fan coming through.
Johann Kraus (in the comic, and I assume in the movie) is a medium and empath who's body was destroyed while he was out-of-body during a seance. The BPRD came in time to build him a "containment suit" to hold his ectoplasmic soul. In the comics it's sort of a man shaped balloon but in the movie it looks more like a diving suit. Johann is German and was a dignified old chap with a beard before his transformation and subsequent career as evil-fighting BPRD agent.
Here's Guillermo del Toro's response on the HBII message board: