DEMETRIUS III. (d. 88 B.c.), called Euergetes and Philometor, was the son of Antiochus VIII. Grypus. By the assistance of Ptolemy X. Lathyrus, king of Egypt, he recovered part of his Syrian dominions from Antiochus X. Eusebes, and held his court at Damascus. In attempting to dethrone his brother, Philip Epiphanes, he was defeated by the Arabs and Parthians, and kept prisoner in Parthia by King Mithridates until his death.