Who was the brother of Moses and first high priest?

The brother of Moses and first high priest was Aaron.

Aaron was the elder brother of Moses and the brother of Miriam in the Old Testament. When Moses hesitates to speak before Pharaoh, Aaron acts as his spokesman. He therefore plays a major public role during the Israelites’ confrontation with Egypt and their escape from slavery.

Aaron’s more distinctive religious role emerges after the Exodus. He is appointed Israel’s first high priest, while his sons Nadab, Abihu, Eleazar, and Ithamar serve in the priestly line. The Book of Leviticus describes rituals, sacrifices, and regulations associated with this office and with the Tabernacle, the portable sanctuary of the wilderness period.

Aaron is also associated with serious failures. During Moses’ absence on Mount Sinai, Aaron helps create the golden calf. Later, he and Moses are punished for an episode involving the wilderness community and a rock. Aaron dies on Mount Hor, and his son Eleazar succeeds him as high priest. Joshua was Moses’ successor as leader, not his brother.