John Hyrcanus II (/hərˈkeɪnəs/, Hebrew: יוחנן הרקנוס Yohanan Hurqanos; died 30 BCE), a member of the Hasmonean dynasty, was the High Priest of Israel in the 1st century BCE. He was also briefly king of Judea (67–66 BCE) and then the ethnarch of Judea, probably over the period 47–40 BCE.

Hyrcanus was the elder of two sons born to Alexander Jannaeus, King and High Priest, and Salome Alexandra. After Alexander died in 76 BCE, his widow succeeded to the throne as queen of Judea. She installed Hyrcanus as High Priest in 73 BCE. When Salome died in 67 BCE, she named Hyrcanus as her successor as ruler of Judea as well, but soon he and his younger brother, Aristobulus II, began fighting over who had the right to the throne.

Alexander had numerous conflicts with the Pharisees. However, Hyrcanus was supported by the Pharisees, especially later in his tenure.

Hyrcanus had scarcely reigned three months when Aristobulus II rose in rebellion. Hyrcanus advanced against Aristobulus at the head of his forces. When the brothers met in battle near Jericho, many of Hyrcanus' soldiers defected, joining forces with Aristobulus, thereby giving the latter the victory. Hyrcanus took refuge in the citadel of Jerusalem; but Aristobulus' capture of the Temple compelled Hyrcanus to surrender. A peace was then concluded, according to the terms of which Hyrcanus was to renounce the throne and the office of High Priest, but was to enjoy the revenues of the latter office.

This agreement did not last for long, as Antipater the Idumaean convinced Hyrcanus that Aristobulus was planning his death and to take refuge with Aretas III, King of the Nabataeans. The Nabataeans advanced toward Jerusalem with an army of 50,000 men and besieged the city for several months during the rebellion.

This agreement did not last. Hyrcanus feared that Aristobulus was planning his death. Such fears were furthered by Hyrcanus' adviser, Antipater. According to Josephus, Antipater sought to control Judea by putting the weak Hyrcanus back onto the throne. Hyrcanus took refuge with Aretas III, King of the Nabataeans, who had been bribed by Antipater into supporting Hyrcanus' cause through the promise of returning Arabian towns taken by the Hasmoneans.

The Nabataeans advanced toward Jerusalem with an army of 50,000, took the city and besieged the Temple where Aristobulus had taken refuge for several months. During the siege, Josephus states that the adherents of Hyrcanus stoned the pious Onias (Honi ha'Me'agel, also Khoni or Choni ha-Me'agel), who had refused to pray for the demise of their opponents, and further angered the priests who were fighting along with Aristobulus by selling them cattle for the paschal sacrifice for the enormous price of one thousand drachmae and then refused to deliver the promised animals for the sacrifice.(Antiquities of the Jews Book 14, 2:2)

During the Roman civil war, general Pompey defeated armies of the kingdoms of Pontus and the Seleucids. He sent his deputy Marcus Aemilius Scaurus to take possession of Seleucid Syria.