Apollonius of Citium was a physician from the city of Citium in Cyprus who lived and worked in the 1st century BCE. He was a member of the Empiricist school of medicine, which emphasized practical observation and experience over abstract theory. Apollonius studied in Alexandria and was associated with the court of Ptolemy XII, to whom he dedicated his major work.

He is known for a single surviving treatise: a detailed commentary on the Hippocratic text On Joints, which deals with surgical procedures for treating dislocations and fractures. This work survives in a 10th-century Byzantine manuscript that includes detailed illustrations of the techniques described. These drawings are considered the oldest surviving medical illustrations from the ancient world.

According to modern scholars, Apollonius is an important figure for understanding how Hippocratic medicine was studied and applied in the Hellenistic period. His commentary provides a direct view into the practical teaching of surgery. The survival of his illustrated manuscript is also significant for the history of medical art and the transmission of technical knowledge from antiquity through the Middle Ages.