Hellboy: 20 Easter Eggs And References Explained

One of the most exciting reveals in the entire Hellboy film comes in the second post-credits scenes, wherein Baba Yaga sets her pet undead warrior, Koshchei the Deathless, after Hellboy in revenge for him breaking her pact.

This almost perfectly mirrors the plot of Hellboy: Darkness Calls, where Baba Yaga similarly uses her possession of Koshchei's soul to send the man after Hellboy. Unable to die, and capable of recovering quickly from staggering wounds, there's a very real chance that Koshchei could make for one of the most brutal and impressive fights the superhero franchise has ever seen.

While Hellboy's reviews make it fairly likely that a sequel to the film will not be considered, the concept of Koshchei featuring in it almost makes it worth producing for that alone.