'I have a message from Hell, Thorn. Die!' -Hollow-Thorn, Series III, Chapter 67

Appears in: Series III, Chapter 67

The Hollow-Thorns were created by stand-in ruler of Hell, Natica, to get rid of Thorn, who they saw as an obstacle. They were basically created by travelling through time and collecting Thorns, but removing their identity so they did not cause a time paradox. This, however, resulted in the Hollow-Thorns being incredibly weak, and the gang defeated them very easily.