Anaximenes of Lampsacus was a 4th-century BCE Greek historian and rhetorician, a pupil of Diogenes the Cynic and Zoilus. He is most notable for his association with Alexander the Great, whom he taught in rhetoric and accompanied on campaign, dedicating historical works to him. His career was marked by a noted rivalry with the historian Theopompus.

His major works, most now lost, include the Philippica, a history of Philip II of Macedon, and On Alexander. He also wrote a Hellenica and a work on city foundations. He is credibly identified as the true author of the Rhetorica ad Alexandrum, a surviving rhetorical treatise long misattributed to Aristotle.

Anaximenes is significant primarily as the likely author of the Rhetorica ad Alexandrum, the oldest surviving Greek handbook on rhetoric, which predates Aristotle’s work. As a contemporary historian of Philip and Alexander, his lost works were an important early source for the rise of Macedon, though ancient critics noted their bias.