TempleOS is a Biblical-themed lightweight operating system (OS) designed to be the Third Temple from the Hebrew Bible. It was created by American computer programmer Terry A. Davis, who developed it alone over the course of a decade after a series of manic episodes that he later described as a revelation from God. TempleOS could be considered as an example of coding as an art form, with the nature of his psychological instability and its influence over the project lending to comparisons to similar outsider art.