Gaius Stertinius Xenophon (c. 10 BC – 54 AD), often referred to in ancient literature as simply Xenophon, was a physician who served the Roman Emperor, Claudius, the fourth member of the Julio-Claudian dynasty. Xenophon is primarily remembered for his suspected involvement and collaboration in the murder of Claudius by poison. Later, Xenophon spent time serving in the military, and it was through this participation in the armed forces that Claudius first became aware of Xenophon's renown as a physician. As a result, Xenophon become Claudius' personal physician.