In this continuation to the adventure of the demon superhero, an evil elf breaks an ancient pact between humans and creatures, as he declares war against humanity. He is on a mission to release The Golden Army, a deadly group of fighting machines that can destroy the human race. As Hell on Earth is ready to erupt, Hellboy and his crew set out to defeat the evil prince before The Golden Army can destroy humanity's existence.

Peter Jackson approached Guillermo del Toro to direct Halo (2012), and even though del Toro considered it, he turned the offer down so he could direct this sequel. Also, Del Toro turned down I Am Legend (2007), One Missed Call (2008), and Harry Potter and the Half-Blood Prince (2009) for the same reason.

Hellboy:
I know; I'm ugly!

Errors made by characters (possibly deliberate errors by the filmmakers): When the tooth fairies attack, Abe says that they feed mostly on calcium and go for the teeth first, yet when the devoured body of a BPRD agent is shown, all the flesh has been stripped but the skeleton and teeth are clearly fully intact.

Written by J. Fred Coots, Haven Gillespie
Performed by Eddy Arnold
Courtesy of RCA Nashville
By Arrangement with Sony BMG Music Entertainment