Phlegon of Tralles was a Greek writer of the 2nd century CE and a freedman of the emperor Hadrian, originating from the city of Tralles in Lydia. His position as an imperial freedman places him within the network of educated Greek intellectuals serving the Roman imperial court.

His extant work, surviving in fragments, consists primarily of compilations. These include On Marvels, a paradoxographical collection of incredible stories about monsters, ghosts, and hermaphrodites; the Olympiads, a chronological history from 776 BCE to 137–141 CE; and On Long-Lived Persons, a catalog of individuals who achieved extreme old age.

Phlegon is a significant representative of imperial-era paradoxography. His On Marvels is a key source for ancient conceptions of the fantastic, while his Olympiads provided a chronological framework utilized by later historians like Eusebius. He exemplifies the cultural output of Greek intellectuals integrated into the Roman administrative system.