Berossus was a Babylonian priest and scholar who lived in the early 3rd century BCE, during the Hellenistic period. He served the god Bel-Marduk and wrote under the rule of the Seleucid king Antiochus I. His name is a Greek version of a Babylonian name meaning "Bel is his shepherd." Like the Egyptian historian Manetho, he wrote a Greek account of his native civilization for its new Macedonian rulers, aiming to showcase its ancient wisdom. Later traditions claim he founded a school of astrology on the Greek island of Kos, but scholars debate the accuracy of this story.

His major work was the Babyloniaca, a three-volume history of Babylonia. It covered events from the creation of the world up to the conquests of Alexander the Great. This work is now lost and survives only as fragments quoted by later historians and chroniclers, such as Josephus and Eusebius.

According to modern scholars, Berossus's work was a crucial bridge between Mesopotamian and Greek culture. As a priest, he had access to ancient cuneiform records and Babylonian myths, which he synthesized into a Greek narrative. His history transmitted foundational Babylonian stories, like that of the sage Oannes who brought civilization to humanity, to the classical world. Although the original text is lost, these preserved fragments were vital for ancient Greek, Roman, and later medieval scholars, shaping the classical world's understanding of Babylonian history, astronomy, and cosmology.