Demetrius I (of Macedonia), called Poliorcetes (“besieger of cities”) (337?-283 bc), king of Macedonia (294-283 bc). He was the son of King Antigonus I, called Monophthalmus, a general of Alexander the Great. In the wars for power and territory after Alexander's death, both Antigonus and Demetrius participated actively. Demetrius defeated Ptolemy I, king of Egypt, in a battle (306 bc) at Salamís, on the island of Cyprus. In 294 bc he murdered his rival Alexander, son of Cassander, and seized Macedonia, but six years later he was driven out by an alliance of Pyrrhus, king of Epirus and Lysimachus, king of Thrace. Demetrius sought refuge with Seleucus I, king of Syria, but was confined until his death, when his son, Antigonus II Gonatas, claimed the throne of Macedonia.

Demetrius I (of Syria), called Soter (187?-150 bc), king of Syria (162-150 bc), son of Seleucus IV Philopator). Held a hostage in Rome during the reigns of his father and of his uncle, Antiochus IV Epiphanes, he escaped in 163 bc and deposed and killed his cousin, Antiochus V Eupator, who had occupied the Syrian throne on the death of his father, Antiochus IV. The reign of Demetrius I was marked by warfare against the Jews, who were then ruled by the Maccabees, against the Cappadocians, and against the Medes. He was named Soter (Greek, “Savior”) because he liberated the Babylonians from the Median satrap Timarchus (?-160? bc). Demetrius I was killed in battle while resisting the usurpation of Alexander Balas (reigned 150-145 bc), a youth from Smyrna pretending to be the son of Antiochus IV Epiphanes and backed by Rome and Syria's neighbors.

Demetrius II (of Macedonia) (278?-229 bc), king of Macedonia (239-229 bc). The son of Antigonus II Gonatas, Demetrius was opposed on his accession to the throne by an alliance of the Aetolian and Achaean leagues, which opposed Macedonian power in Greece. In 237-236 bc he occupied Boeotia and Megara but suffered a setback in 231 bc when Epirus joined the Achaeans and Aetolians. The following year he was defeated by the Dardanians, and he died soon after, leaving Macedonia in a weakened state.

Demetrius II (of Syria)

Demetrius II (of Syria), called Nicator (?-125? bc), king of Syria (145-139 bc, 129-125 bc), son of Demetrius I. With the aid of Ptolemy VI, king of Egypt, he deposed and killed the usurper Alexander Balas (reigned 150-145 bc) and became king of Syria in 145 bc. Demetrius married his predecessor's widow, Cleopatra Thea (?-120? bc), who was the daughter of Ptolemy VI. In 140 bc, during a war with Parthia, Demetrius was taken prisoner. In captivity he married Rodogune, daughter of the Parthian king Mithridates I. Demetrius II returned to Syria in 129 bc. His brother, Antiochus VII, who had usurped the throne in 139 bc and married Cleopatra Thea, was killed in battle in 127 bc. Demetrius II then regained the crown and reigned until his assassination two years later. His son, Seleucus V, succeeded him but enjoyed a short reign; he was put to death by his mother, Cleopatra Thea, in the same year.

Demetrius III, called Eukairos or Philometor (?-88? bc), king of Syria (95-88 bc), grandson of Demetrius II. In 95 bc, with the aid of Ptolemy IX, at that time the king of Cyprus, Demetrius III gained the throne of Syria and was joint ruler of all Syria with his brother Philip I, against whom for a time he waged a civil war. During a war with Parthia, Demetrius III was captured; he died while in captivity. Philip I was deposed in 84 bc.