Hellboymake-up, after a request from a charity for sick children.
The 62-year-old actor spent a day with the six-year-old, named only as Zachary by The Hollywood Reporter, who is undergoing treatment for leukaemia.
Perlman had been contacted by Spectral Motion, the company which handled the special effects on Hellboy and Hellboy 2, and "loved the idea and donned the make-up once more".
And the youngster was also made up into a mini-Hellboy himself as an additional treat.
The visit was arranged by the Make-A-Wish Foundation, a charity which organises treats for sick kids.