The Flame Keepers' Circle, also known as the Esoterica, is an influential cult that worships an extradimensional being known as Diagon, who apparently visited Earth at the dawn of mankind to bring knowledge of fire and promised to return to bring Earth to a Utopian state of prosperity. They appeared as an antagonistic group in the Ben 10 series, and both the Flame Keepers' Circle and the Esoterica are also the sworn enemies of the Forever Knights. After Ben's last epic battle with Diagon and Vilgax, the Flame Keepers Circle and the Esoterica were disbanded.