Who was the chief of Nebuchadnezzar's court officials, told to bring in young Israelites?

Answer: Ashpenaz

The king ordered Ashpenaz, chief of his court officials, to bring in young Israelites of royal and noble birth to be trained.

“Then the king ordered Ashpenaz, the chief of his court officials, to bring in some Israelites from the royal family and the nobility—”— Daniel 1:3 (BSB)