Halla, in D. J. MacHale's Pendragon, refers to "everything. Every territory, every person, every living thing, every time there ever was"
A term used in the series Pendragon where Flumes were portals of halla between territories that must only be accessible by travelers. In Pendragon, travelers from ten territories tried to stop Saint Dane from crumbling down Halla.
Halla consists of ten territories: Zadaa, Denduron, Cloral, Quillian, Eelong, Ibara, Veelox, First Earth, Second Earth, and Third Earth