In "Time Capsule," It's somewhat implied that Zorp may have been killed by religious rivals of the Reasonabilists, as the town slogan after the Reasonabilists lost control over Pawnee is "Zorp is dead. Long live Zorp." This would also explain why Zorp did not show up for the destruction of the world. However, it's undetermined on how accurate this slogan is.
Zorp was first brought into the mainstream by Lou Prozotovich, an office supply salesman who wrote two books, "Organize It!" and "Organize It 2: Engage With Zorp!" The second is said to not get very good until Zorp shows up.