Akhenaten

Akhenaten, originally Amenhotep IV, ruled Egypt during the Eighteenth Dynasty and caused quite a stir by ditching the centuries-old pantheon of gods in favor of a single deity, Aten. This wasn't just a minor tweak to the liturgical calendar; it was a wholesale religious revolution, earning him the nickname "the heretic king." Good thing he didn't try to introduce concept albums and avocado toast to ancient Egypt; that really would have been too much.

His reign was marked by a fervent, almost obsessive, devotion to Aten, prompting him to close temples of other gods, deface their images, and even move the capital to a new city, Akhetaten (modern Amarna), dedicated solely to his new sun god. Talk about putting all your eggs in one basket – or all your divine power in one sun disk.

While his religious reforms were radical, they were also remarkably short-lived. After his death, Egypt swiftly reverted to its traditional polytheism, and his name and monuments were systematically erased from history. It seems the populace wasn't quite ready for a monotheistic mic drop, preferring their familiar array of animal-headed deities. Perhaps a more gradual rollout would have been prudent.