Theopompus (thēˌōpŏmˈpəs) [key], fl. 4th cent. B.C., Greek historian and rhetorician, b. Chios. He studied with the orator Isocrates and became a friend of both Philip and Alexander of Macedon. His pro-Macedonian sympathies often caused trouble with his fellow Greeks. He wrote the Hellenica, a history of Greece from 411 B.C. to 394 B.C., and the Philippica, a discursive chronicle of Philip's life.