And there appeared another wonder in heaven; {4} and behold a great red dragon, having {5} seven heads and ten {6} horns, and seven crowns upon his heads.

(4) That is the devil or Satan, see Re 12:9, mighty, angry and full of wrath.

(5) By this to withstand those seven churches spoken of, that is, the catholic church, and that with kingly objects and tyrannical magnificence: signified by the crowns set on his heads, as if they belonged to him by the proper right, without controversy: as also he boasted to Christ; See Mt 4:9 Re 13:1.

(6) More than the horns of the Lamb, or than the churches are: so well equipped does the tyrant brag himself to be, to do all manner of wickedness.

People's New Testament

12:3 Behold a great red dragon. Another wonder is seen, also in the sky, a great serpent-like figure, red, with seven heads and ten horns. This figure, we learn from Re 12:9 is a devilish manifestation. The devil uses it for his purposes. The red color implies a persecuting power. Having seven heads and ten horns. The seven heads are explained in Re 17:9, where the seven-headed beast appears again, to be seven mountains, and also seven kingdoms; the ten horns are there said to be ten kingdoms which did not yet exist. We have also this monster appearing substantially in Da 7:7. I will discuss it more particularly in chapter 17 (see PNT Re 17:12), but will here say that there is little doubt that it represents the persecuting powers of the earth which have opposed God and his Israel; the great world powers arrayed against God. This world power appears as Pagan Rome in the persecution of the Woman; the Church. The dragon was the standard of Pagan Rome in the third century, as testified by many ancient writers.

Wesley's Notes

12:3 And behold a great red dragon - His fiery - red colour denoting his disposition. Having seven heads - Implying vast wisdom. And ten horns - Perhaps on the seventh head; emblems of mighty power and strength, which he still retained. And seven diadems on his heads - Not properly crowns, but costly bindings, such as kings anciently wore; for, though fallen, he was a great potentate still, even the prince of this world.

King James Translators' Notes

wonder: or, sign

Jamieson-Fausset-Brown Bible Commentary

3. appeared-"was seen."

wonder-Greek, "semeion," "sign."

red-So A and Vulgate read. But B, C, and Coptic read, "of fire." In either case, the color of the dragon implies his fiery rage as a murderer from the beginning. His representative, the beast, corresponds, having seven heads and ten horns (the number of horns on the fourth beast of Da 7:7; Re 13:1). But there, ten crowns are on the ten horns (for before the end, the fourth empire is divided into ten kingdoms); here, seven crowns (rather, "diadems," Greek, "diademata," not stephanoi, "wreaths") are upon his seven heads. In Da 7:4-7 the Antichristian powers up to Christ's second coming are represented by four beasts, which have among them seven heads, that is, the first, second, and fourth beasts having one head each, the third, four heads. His universal dominion as prince of this fallen world is implied by the seven diadems (contrast the "many diadems on Christ's head," Re 19:12, when coming to destroy him and his), the caricature of the seven Spirits of God. His worldly instruments of power are marked by the ten horns, ten being the number of the world. It marks his self-contradictions that he and the beast bear both the number seven (the divine number) and ten (the world number).

Matthew Henry's Concise Commentary

12:1-6 The church, under the emblem of a woman, the mother of believers, was seen by the apostle in vision, in heaven. She was clothed with the sun, justified, sanctified, and shining by union with Christ, the Sun of Righteousness. The moon was under her feet; she was superior to the reflected and feebler light of the revelation made by Moses. Having on her head a crown of twelve stars; the doctrine of the gospel, preached by the twelve apostles, is a crown of glory to all true believers. As in pain to bring forth a holy family; desirous that the conviction of sinners might end in their conversion. A dragon is a known emblem of Satan, and his chief agents, or those who govern for him on earth, at that time the pagan empire of Rome, the city built upon seven hills. As having ten horns, divided into ten kingdoms. Having seven crowns, representing seven forms of government. As drawing with his tail a third part of the stars in heaven, and casting them down to the earth; persecuting and seducing the ministers and teachers. As watchful to crush the Christian religion; but in spite of the opposition of enemies, the church brought forth a manly issue of true and faithful professors, in whom Christ was truly formed anew; even the mystery of Christ, that Son of God who should rule the nations, and in whose right his members partake the same glory. This blessed offspring was protected of God.