His likely full Hebrew name was Jonathan; he may have been the High Priest Jonathan, rather than his great-uncle of the same name, who established the Masada fortress. Under the name King Yannai, he appears as a wicked tyrant in the Talmud, reflecting his conflict with the Pharisee party. He is among the more colorful historical figures despite being little known, however, outside specialized history. He and his widow (who became queen regnant after his death) had substantial impact on the subsequent development of Judaism and Christianity.
An avid supporter of the aristocratic priestly faction known as the Sadducees, his reign was constantly challenged by opponents, among them a brother with a rival claim to the throne, and the populist urban-based Pharisee party.
At the beginning of his reign Alexander Jannaeus halted the suppression of the Pharisees and the Sages for a while, under the influence of his wife Salome Alexandra (said to be the sister of the great Jewish sage Shimon ben Shetach). This gave him time and resources to increase his power and prestige by extending the territory under his rule through war and conquest. As his power grew, however, he enlisted foreign soldiers to suppress his own people and eliminate the Pharisees.
One year during the Jewish holiday of Sukkot, Alexander Jannaeus, while officiating as the High Priest (Kohen Gadol) at the Temple in Jerusalem, demonstrated his support of the Sadducees by denying the law of the water libation. The crowd responded with shock at his mockery and showed their displeasure by pelting Alexander with the etrogim (citrons) that they were holding in their hands. Unwittingly, the crowd had played right into Alexander's hands. He had intended to incite the people to riot and his soldiers fell upon the crowd at his command. The soldiers slew more than 6,000 people in the Temple courtyard.
A civil war started, in which the Pharisees allied with the Seleucid king Demetrius III against Alexander Jannaeus. He first retreated, but then managed to oust his rivals thanks to popular support against the Seleucid invasion of Judea. During the civil war, Alexander Jannaeus suppressed his rivals brutally, killing his brother and many leading Pharisees. The New Century Book of Facts writes:
Alexander Jannaeus showed considerable competence as a military leader, repelling invaders and expanding the country's borders to the west and south. He was defeated by Ptolemy Lathyrus in Galilee; made an alliance with Cleopatra and drove Ptolemy out. By the end of his rule, the borders of his state would exceed that of David and extend to Gaza and far into Jordan.
Alexander Jannaeus was the first of the Jewish kings to introduce the "eight-ray star" or "eight-spoked wheel" symbol, in his bronze "Widow's mite" coins, in combination with the wide-spread Seleucid numismatic symbol of the anchor. These coins are thought to be the ones referred to in the Bible in Luke 21:1-4:
Depending on the make, the star symbol can be shown with straight spokes connected to the outside circle, in a style rather indicative of a wheel. On others, the spokes can have a more "flame-like" shape, more indicative of the representation of a star within a diadem.
It is not clear what the wheel or star may exactly symbolize, and interpretations vary, from the morning star, to the sun or the heavens. The influence of some Persian symbols of a star within a diadem, or the eight-spoked Buddhist wheel (see the coins of the Indo-Greek king Menander I with this symbol) have also been suggested. The eight-spoked Macedonian star (a variation of which is the Vergina Sun), emblem of the royal Argead dynasty and the ancient kingdom of Macedonia, within a Hellenistic diadem symbolizing royalty (many of the coins depict a small knot with two ends on top of the diadem), seem to be the most probable source for this symbol.