The Man is a minor character in Hellboy VS Demonic Toys. He is an older version of The Kid from Demonic Toys
Hellboy VS Demonic Toys (fanfiction/unexistant film)
He is first mentioned when he gives the toys to Custer Kurtz. He reveals a backstory about how he tried to kill Judith Grey and Mr. Static killing her. After a while, he fades away and never is heard from again in the fanfiction.
An early draft of the opening credits features The Kid narrating.
In the film, The Kid is played by Daniel Cerny, reprising his role respectively, who was renamed The Man due to aging. He was voiced by LW Leon, who also played The Demon King in the film.
Hellboy VS Demonic Toys II (fanfiction/unexistant film)
The Man-Demon is briefly seen. Then, in the final battle, he makes a cameo appearance.
Here's a link to The Kid on Fandom Villains Wiki