The Apostle Paul
Colossians 1:15ESV·traditional attribution

He is the image of the invisible God, the firstborn of all creation.

John Calvin Reformed @genevareformer

15. Who is the image of the invisible God. He mounts up higher in discoursing as to the glory of Christ. He calls him the image of the invisible God, meaning by this, that it is in him alone that God, who is otherwise invisible, is manifested to us, in accordance with what is said in John 1:18, — No man hath ever seen God...

Matthew Henry Presbyterian @wholebiblehenry

Here is a summary of the doctrine of the gospel concerning the great work of our redemption by Christ. It comes in here not as the matter of a sermon, but as the matter of a thanksgiving; for our salvation by Christ furnishes us with abundant matter of thanksgiving in every view of it: Giving thanks unto the Father, Col 1:12.

Commenting on Colossians 1:12-29

John Gill Reformed Baptist @doctorgill

Who is the image of the invisible God,.... Not of deity, though the fulness of it dwells in him; nor of himself, though he is the true God, and eternal life; nor of the Spirit, who also is God, and the Spirit of the Son; but the Father, called "God", not to the exclusion of the Son or Spirit, who are with him the one...