John the Apostle
John 16:8BSB·traditional attribution

And when He comes, He will convict the world in regard to sin and righteousness and judgment:

John Calvin Reformed @genevareformer

8. And when he is come. Passing by the diversity of expositions, which we have received in consequence of the obscurity of the passage, I shall only state what appears to me to be in accordance with Christ’s true meaning.

Matthew Henry Presbyterian @wholebiblehenry

As it was usual with the Old Testament prophets to comfort the church in its calamities with the promise of the Messiah (Isa 9:6; Mic 5:6; Zac 3:8); so, the Messiah being come, the promise of the Spirit was the great cordial, and is still. Three things we have here concerning the Comforter's coming: - I. That Christ's departure was absolutely necessary to the Comforter's coming, Joh 16:7.

Commenting on John 16:7-15

John Gill Reformed Baptist @doctorgill

And when he is come,.... The coming of the Spirit here, chiefly designs his descent upon the apostles, at the day of "Pentecost": as the things ascribed to him, and which were then done by him, clearly show; though it may also include his coming along with, and by the ministration of the Gospel, into the hearts of his people at conversion, in all after...