Eliezer ben Jacob I (Hebrew: אליעזר בן יעקב) was a Tanna of the 1st century; contemporary of Eleazar Chisma and Eliezer ben Hyrcanus, and senior to Judah ben Ilai. Of his personal history nothing is known, except that he had seen the Temple at Jerusalem and was familiar with the specific purposes of its many apartments, a subject on which he was considered an authority. Some of the details, however, he eventually forgot, and was reminded of them by Abba Saul ben Batnit. He is buried near the old Kefar Hanaiah, in Galilee.