Bion of Abdera was a Greek mathematician and astronomer of the 4th century BCE. He is known only from brief mentions by later authors, primarily the Roman architect Vitruvius, who cites him as an authority on sundial construction. A contemporary of Democritus from the same city, Bion is situated within Abdera’s intellectual milieu, though no direct philosophical affiliation is recorded.

His sole attested work is On Weather Signs, a lost text on meteorological prognostication. The Roman scholar Varro references Bion as an authority on weather signs derived from astronomical observations.

Bion’s significance lies in his inclusion within the traditions of Greek gnomonics and parapegmatic literature. Vitruvius places him alongside figures like Eudoxus in the science of sundials, while Varro’s citation links him to the practical, observational blending of astronomy, meteorology, and agriculture. He represents an applied mathematical tradition of the Classical period, though his contributions remain obscure due to the complete loss of his work.