Aristobulus I ruled Israel as king from 104 to 103 BC.
Aristobulus was the son of John Hyrcanus. He had hoped to change the government into a kingdom so upon his father's death he took the title "king" which his predecessors had not done. Because of this he was the first priest-king of the Jewish people.
During his brief reign he extended the kingdom's territory into Iturea in southern Lebanon. He required his conquered subjects to convert to Judaism. When he died in 103 BC his brother Alexander Jannaeus succeeded him.