Gaius Julius Alexander (Greek: Γαίος Ιούλιος Αλέξανδρος) was a Herodian Prince that lived in the 1st century and 2nd century in the Roman Empire.
Alexander was of Jewish, Nabataean, Edomite, Greek, Armenian and Persian ancestry. He was the son of the Herodian Prince, later king Tigranes VI of Armenia and his wife Opgalli. His father in the spring of 58 was crowned as king of Armenia by Roman Emperor Nero in Rome and ruled until 63. Alexander had a sister called Julia, who married the Anatolian Roman Senator Marcus Plancius Varus.
Alexander's paternal grandparents were the Judean Prince Alexander and his unnamed wife. Through his father, Alexander was the great-grandson of Cappadocian Princess Glaphyra and Judean Prince Alexander. He was the great-great-grandson of king Archelaus of Cappadocia, king of Judea Herod the Great and his wife Mariamne. Alexander along with his sister and father were the last of the known descendants of the kings of Cappadocia. Prior to the year 58, little is known on Alexander's life. He was an apostate to Judaism. It is unlikely that he attempted to exert influence on Judean Politics.
Tigranes had arranged with king Antiochus IV of Commagene, who he was an ally to when he was crowned king, to marry Alexander to Antiochus' daughter Julia Iotapa. The betrothal was held in Rome after Tigranes' coronation. The marriage was mostly a political alliance that occurred between the fathers of Alexander, Iotapa and possibly Nero. After the betrothal, Nero crowned Alexander and Iotapa as Roman client rulers of the small Cilician region of Cetis, that had previously been ruled by Alexander's Seleucid ancestors, his ancestor Archelaus of Cappadocia, the son of this, Archelaus of Cilicia, and Antiochus IV. The Cilician city of Elaiussa Sebaste was made a part of their kingdom. Alexander and Iotapa ruled Cetis from 58 until at least 72.
Little is known on the marriage and reign of Alexander and Iotapa. Iotapa bore Alexander three children: two sons Gaius Julius Agrippa, Gaius Julius Alexander Berenicianus and a daughter Julia Iotapa. Their children were born and raised in Cetis. A possible descendant from their marriage was the usurper Jotapianus, who lived in the 3rd century. His name and the names Alexander gave his sons indicate that their family connections from the Herodian Dynasty were not wholly broken. In Vespasian’s reign (69-79) or Titus’ reign (79-81), Alexander had entered the Roman Senate; had reached and served either as a consul or suffect consul during Trajan’s reign before 109.