The Spider-Man 3 actor will be playing the role of Lobster Johnson, a crustacean-themed vigilante first introduced by Mike Mignola in the comics in 2000. Sort of like a mix of Batman and Captain America, Johnson (sometimes known simply as "the Lobster") violently fought crime and supernatural threats during the Great Depression in New York City, often killing adversaries or burning his lobster claw logo into their flesh. To the public, he's didn't exist, thought to be an imaginary character of comic books, pulp novels, and serial films.
He also opposed Nazism and died in a 1939 attempt to stop a German rocket launch in Austria, which was meant to put the Third Reich in contact with Lovecraftian entities that would make them invincible. Even after his death, Johnson returned in the form of a ghost, forming a trusting relationship with Hellboy and Johann Kraus.
However, it is somewhat uncommon for a big budget blockbuster to make a new and high profile casting addition so late in the game, particularly when a trailer has already been cut together. The first trailer was shown at New York Comic Con in early October and later leaked online via cell phone footage, but never officially released.
Maybe that's why Lionsgate has hesitated to release the existing trailer to the public; they want to make sure all of the reshoots (assuming that's what Haden Church has signed on for) are in order before the rest of the world sees the first footage. If we had to guess, we'd say Lobster Johnson will appear in a flashback sequence to Hellboy's arrival on Earth during Project Ragnarok, a Nazi effort to free the Ogdru Jahad (yet another cosmic entity of pure evil, hatred, and destruction) in 1944.
While Johnson died long before that in the comics, the movie may want to keep him alive to set itself apart from Guillermo del Toro's film, which already depicted Ragnarok in a live-action format. He could die during this pivotal Allied assault (that let loose the Right Hand of Doom) and later provide support to Hellboy in the modern day as a ghost.
Directed by Neil Marshall, Hellboy hits theaters on April 12.