Hellboy: 20 Easter Eggs And References Explained
19. Hellboy's Mother
The tale surrounding Hellboy's mother, Sarah Hughes, is that she married the demon Azzael, essentially sold her soul to him, and then gave birth to the child that would go on to be known as Hellboy.
It's particularly interesting that this element of the plot remains the same in the movie as it does in the comics, as it suggests that Hellboy's demonic father and siblings also exist in this universe - opening the potential for the (admittedly unlikely) sequel to feature them in some capacity.