Pinface is an inter-dimentional demon. Pinface's inter-dimentional powers are somehow connected to his Rubiks-esque puzzle cube, which, if kept solved, keeps him trapped in the Netherworld.
Pinface has purple skin, wears a long dark purple robe, but his most distint physical feature that he also shares with his sister, (and possibly with rest of his family,) is that he has bowling pins growing out of his skull - something he's sensitive about as people will stare at him.
According to Grim, when Pinface and his younger sister were both still kids, they used to live across the street from a then-younger Grim, in the Underworld. When Pinface's Father got a new job, his family had to relocate to the Netherworld, another dimention from the Underworld.
Some years later, Pinface's younger sister and Grim met up with each other at the Netherworld mall and hung out and dated briefly until Grim broke it off, something that Pinface seems upset about, as she never understood herself why Grim broke up with her. Grim claims it was because of the bowling pins sticking out of her head constantly poking into his eye sockets whenever she and Grim tried making out with each other.
Later, after 4 years of trying, Grim was able to bar Pinface from coming to Earth by solving a mysterious Rubiks-esq puzzle cube that is somehow connected to Pinface's inter-dimentional powers. Grim would then place the cube inside of his magic trunk for safekeeping.
In the events of "The Show that Dare Not Speak Its Name," Billy (after ignoring Grim's warnings to stay out of his trunk for the umpteenth time) rumages through Grim's trunk out of mind-numbing boredom and his attention is caught the puzzle cube with a mysterious voice coming from within it. Billy is tricked into playing with the cube after first trying to get a promise out of it that it wouldn't do anything bad and then settling for a promise from the voice that it wouldn't try hitting on his mom.
Released from the cube, Pinface sets about taking over the world after first kicking Billy out of his own house. Summoning more demons from the Netherworld, Pinface soon becomes asperated when the demons are more interested in throwing a wild house party. Billy, accompanied by Mandy, confront Pinface together in Billy's kitchen, ordering him to leave or else they'll get Grim to come and banish him. However, Pinface is unconcerned, even amused by their assumption - until he gets a shock when he realizes that Grim's standing right behind him.
Grim and Pinface exchange words as Grim explains to Billy and Mandy their past affiliations. After it was demonstrated that Grim coundn't banish Pinface back to the Netherworld with his scythe, Pinface, likewise, banishes Grim to the Netherworld instead. Just when it seems that Pinface is poised to succeed, Harold picked up the disguarded cube and proceeded to "solve" it the same way he "solved" Rubik's Cubes during his childhood, by peeling off the colored squares and re-arranging them into order.
With the puzzle cube "solved" again, Pinface (along with all his minions) were all sent straight back to the Netherworld. He was later seen watching in disgust as his younger sister kept flirting with their new, unhappy houseguest: Grim.
- Both Pinface and his puzzle cube are parodic references to the Hellraiser movie franchise.