The Apostle Paul
Ephesians 3:10BSB·traditional attribution

His purpose was that now, through the church, the manifold wisdom of God should be made known to the rulers and authorities in the heavenly realms,

Geneva Bible Notes Reformed

To the intent that now unto the principalities and powers in heavenly [places] might be known by the church the manifold wisdom of God, (2) The unsuspected calling of the Gentiles was as it were a mirror to the heavenly angels, in which they might behold the marvellous wisdom of God. (c) God always had only one way to save men by: but it had various shapes and forms.

Jamieson-Fausset-Brown Reformed

The design of God in giving Paul grace to proclaim to the Gentiles the mystery of salvation heretofore hidden. now--first: opposed to "hidden from the beginning of the world" (Eph 3:5). unto the principalities and--Greek adds "the" powers--unto the various orders of good angels primarily, as these dwell "in the heavenly places" in the highest sense; "known" to their adoring joy (Ti1 3:16; Pe1 1:12).

William Burkitt Anglican

Observe here, 1. The title given to the holy angels; they are styled principalities and powers, because God makes us of their powerful ministry in governing the kingdoms and principalities of this world: and they are said to be in heavenly places; not as if they were never here upon earth below, but because the ordinary place of their residence is heaven above. Observe, 2.