Abiathar, in the Hebrew Bible, is a son of Ahimelech or Ahijah, High Priest at Nob, the fourth in descent from Eli and the last of Eli's House to be a High Priest.

In Judaism, the High Priest of Israel was the head of the Israelite priesthood. He played a unique role in the worship conducted in the Tabernacle and later in the Temple in Jerusalem, as well as in some non-ritual matters. Like all priests, he was required to be descended from Aaron. But unlike other priests, the high priest followed more restrictive laws, wore unique priestly garments, and was the only priest allowed to perform certain ceremonies.