Shimshai was a state secretary associated with Rehum the chancellor. He participated in opposition to the rebuilding of the temple after the exile by writing to Artaxerxes. His name appears to be related to the sun or to brightness, though its precise explanation is uncertain.
Shimshai is named in the Aramaic correspondence opposing the rebuilding of Jerusalem and the temple. The royal order resulting from that correspondence halted the work for a time.
He served within the Persian administrative setting after the captivity. The name appears in differing forms in the Greek versions, and its etymology has not been generally settled.