And Eleazar the son of Aaron the priest shall be chief over the chief of the Levites, and have the oversight of them that keep the charge of the sanctuary. (Numbers 3:32)
Eleazar was a Kohathite (see Ex. 6:18, 20, 23). He was chief over Elizaphan and all the Kohathites, and as the eldest surviving son of Aaron, was therefore the chief prince or overseer of the Levites.