Temple OS is a lightweight, religiously themed operating system created by American programmer Terry Davis. He led the development over a period of ten years, following a series of psychotic episodes that he later described as divine revelation. TempleOS was intended to resemble the Third Temple prophesied in the Bible, with an interface similar to a mix of DOS and Turbo C. Davis described the operating system as a modern development of the Commodore 64 concept for the x86-64 platform, using a variant of the C language (called "HolyC") instead of BASIC. According to Davis, God commanded him to create an operating system with 16-color graphics, a resolution of 640 × 480, and monophonic sound.The operating system was released in 2013 and was last updated in 2017.
Davis suffered from schizophrenia and was homeless at times. During this time, he posted hours of video on social media, and by the time of his death, he had amassed a following who called him a "programming legend" and compared the creation of TempleOS to building a skyscraper by himself. In 2017, TempleOS was exhibited in France at an art brut exhibition. Davis died in 2018 at the age of 48.