"Who are you?"
This article's name is conjectural, and based off of a fan name. Its contents refer to something that has no verified name.
"Pyramid Head" is a character appearing in Petscop 12. Pyramid Head looks similar to Paul, the only difference is that Pyramid Head has a pyramid as a head.

Pyramid Head

Pyramid Head is found in the quitters room and is also seen for a split second still mirroring Paul when he leaves the quitter's room, until they reach the same point, where Pyramid Head disappears.