"But I will more plainly set forth the manner in which this happens. When the close of the times draws nigh, a great prophet shall be sent from God to turn men to the knowledge of God, and he shall receive the power of doing wonderful things. Wherever men shall not hear him, he will shut up the heaven, and cause it to withhold its rains; he will turn their water into blood, and torment them with thirst and hunger; and if anyone shall endeavor to injure him, fire shall come forth out of his mouth, and shall burn that man."Lactantius
Divine Institutes Bk. 7 Ch. XVII, Vol. 7

"Rev_7:2 “And I saw another angel ascending from the east, having the seal of the living God”] He speaks of Elias the prophet, who is the precursor of the times of Antichrist, for the restoration and establishment of the churches from the great and intolerable persecution. We read that these things are predicted in the opening of the Old and New Testament"Victorinus
On the Apocalypse of John Vol. 7

"And it seems to be indicated by these words, that Elijah was to prepare for the glorious coming of Christ by certain holy words and dispositions in their souls, those who had been made fittest for this, which those upon earth could not have endured, because of the excellency of the glory, unless they had been prepared beforehand by Elijah. And likewise, by Elijah, in this place, I do not understand the soul of that prophet but his spirit and his power; for these it is by which all things shall be restored, (Mat_17:11) so that when they have been restored, and, as a result of that restoration, become capable of receiving the glory of Christ, the Son of God who shall appear in glory may sojourn with them."Origen
Gospel of Matthew Bk. 13 Pt. 1 Sec. 2 Vol. 9

And Trypho said, “This statement also seems to me paradoxical1; namely, that the prophetic Spirit of God, who was in Elijah, was also in John.” To this I replied, “Do you not think that the same thing happened in the case of Joshua the son of Nave (Nun), who succeeded to the command of the people after Moses, when Moses was commanded to lay his hands-on Joshua, and God said to him, I will take of the spirit which is in thee, and put it on him?’” And he said, “Certainly.” “As therefore,” I say, “while Moses was still among men, God took of the spirit which was in Moses and put it on Joshua, even so God was able to cause [the spirit] of Elijah to come upon John;Justin Martyr
Dialogue of Justin with Trypho Ch. XLIX, Vol. 1

"Rev_12:6 “But the woman fled into the wilderness, and there were given to her two great eagle’s wings.”] The aid of the great eagle’s wings - to wit, the gift of prophets - was given to that Catholic Church, whence in the last times a hundred and forty-four thousands of men should believe on the preaching of Elias; but, moreover, he here says that the rest of the people should be found alive on the coming of the Lord. And the Lord says in the Gospel: “Then let them which are in Judea flee to the mountains;” (Luk_21:21) that is, as many as should be gathered together in Judea, let them go to that place which they have ready, and let them be supported there for three years and six months from the presence of the devil."Victorinus
On the Apocalypse of John Vol. 7

"He himself will divide the globe into three ruling powers, when the Antichrist will be raised from Hades. Elijah will first come to seal the beloved ones."Commodianus
Instructions Ch. XLI, Vol. 4

“If therefore Scripture compels you to admit that two advents of Christ were predicted to take place, — one in which He would appear suffering, and dishonored, and without comeliness; but the other in which He would come glorious, and Judge of all, as has been made manifest in many of the fore cited passages, — shall we not suppose that the word of God has proclaimed that Elijah shall be the precursor of the great and terrible day, that is, of His second advent?”Justin Martyr
Dialogue of Justin with Trypho Ch. XLIX, Vol. 1

It is a matter of course that His forerunners must appear first, as He says by Malachi and the angel, “I will send to you Elias the Tishbite before the day of the Lord, the great and notable day, comes; and he shall turn the hearts of the fathers to the children, and the disobedient to the wisdom of the just, lest I come and smite the earth utterly.” (Mal_4:5, Mal_4:6) These, then, shall come and proclaim the manifestation of Christ that is to be from heaven; and they shall also perform signs and wonders, in order that men may be put to shame and turned to repentance for their surpassing wickedness and impiety.Hippolytus
Fragments 2.1 Vol 5