Publius Herennius Dexippus (born c. 210—died after 270) was a Roman historian and Athenian statesman, one of the principal authorities for the history of the mid-3rd century ad.
The Bibliotheca, a 9th-century encyclopaedia by Photius, patriarch of Constantinople, credits Dexippus with three major works: a four-book history of the diadochoi (successors) of Alexander the Great, a history of the struggle of Rome against the Goths from ad 238 until the reign of Aurelian (270–275), and a 12-book annalistic chronicle from legendary times to ad 270. Although none of these survive, numerous fragments have been recognized in the compilations of later historians. Much of the Scythian History survives in the work of the 6th-century historian Zosimus. Some of the extant passages confirm the contemporary view of Dexippus as an imitator of Thucydides. Several Athenian inscriptions attest to the high public offices held by Dexippus, his father, and his children. According to the Augustan History, Dexippus wrote of rallying about 2,000 of his fellow citizens to repel a Gothic attack on Athens in 267.