Ron Perlman spent four hours in the make-up chair to get into his full Hellboy costume to visit a sick child in hospital.
The actor, who played the character in two movies, went all out during his visit to a medical centre in California to surprise a six-year-old boy named Zachary, for the Make-A-Wish Foundation.
Special effects experts at movie company Spectral Motion agreed to help Perlman transform into his superhero alter-ego, and they also did Hellboy make-up for Zachary, who is undergoing treatment for leukaemia.
A post on the company's Facebook.com page reads, "Zachary loved his visit for two very special reasons. It was Zachary's wish to meet Hellboy and also to become Hellboy. When the Make-A-Wish Foundation contacted Spectral Motion with this request, (we) thought it would be fantastic to have Ron Perlman reprise his role for the day. Ron loved the idea and donned the make-up once more... and also ordered a Hellboy-sized meal of burgers, shakes, and fries for Zachary and his family and the entire Spectral crew to enjoy.
"Later in the day, Zachary was transformed into Hellboy with the assistance of make-up artists Lufeng Qu and Neil Winn."