John the Apostle
Revelation 12:3BSB·traditional attribution

Then another sign appeared in heaven: a huge red dragon with seven heads, ten horns, and seven royal crowns on his heads.

Matthew Henry Presbyterian @wholebiblehenry

Here we see that early prophecy eminently fulfilled in which God said he would put enmity between the seed of the woman and the seed of the serpent, Gen 3:15. You will observe, I. The attempts of Satan and his agents to prevent the increase of the church, by devouring her offspring as soon as it was born; of this we have a very lively...

Commenting on Revelation 12:1-11

John Gill Reformed Baptist @doctorgill

And there appeared another wonder in heaven,.... Or "sign"; which represents the woman, or the church's adversary, Satan; not that he was in heaven, in the third heaven, the place of glory and happiness, for out of that he had been cast long ago; but in his great power and authority here on, earth, particularly in the Roman empire, where the church was labouring to...

Albert Barnes Presbyterian @notesbybarnes

Verse 3. And there appeared another wonder in heaven. Represented as in heaven. Barnes on "Re 12:1". That is, he saw this as occurring at the time when the church was thus about to increase. And behold a great red dragon. The word rendered dragon --δρακων-- occurs, in the New Testament, only in the book of Revelation, where it is uniformly rendered as here--dragon: .