Kroenen

Karl Ruprecht Kroenen is a fictional character in the Hellboy comic book series, created by Mike Mignola.

In the comics, Kroenen was a relatively unremarkable Nazi SS scientist, whose most distinguishing characteristic was that he always wore a gas mask and protective bodysuit, which Mignola attributes to a disfiguring accident of some kind.

Director Guillermo del Toro created a significantly expanded biography for the character, to appear as a villain in the 2004 film adaptation.

A German scientist working for the Nazi, and a member of the Thule Society, Dr. Kroenen became one of the top scientists for Project Ragna Rok, and a close disciple of Grigori Rasputin, along with Ilsa Haupstein and Leopold Kurtz. He was present with Rasputin at the secret ritual in Scotland that brought Hellboy to the world.