1 Enoch 15:8-16:1: "But now the giants who were begotten by the spirits and flesh -- they will call them evil spirits upon the earth, for their dwelling will be upon the earth. The spirits that have gone forth from the body of their flesh are evil spirits, for from humans they came into being, and from the holy Watchers was the origin of their creation. Evil spirits they will be upon the earth, and evil spirits they will be called. The spirits of heaven, heaven is their abode, but the spirits begotten in the earth, earth is their abode. And the spirits of the giants lead astray, do violence, make desolate, and attack and wrestle and hurl upon the earth and cause illnesses. They eat nothing but abstain from food and are thirsty and smite. These spirits will rise up against the sons of men and against the women, for they have come forth from them. From the day of the slaughter and destruction and death of the giants, from the soul of whose flesh the spirits are proceeding, they are making desolate without incurring judgment. Thus they will make desolate until the day of the consummation of the great judgment".
Jubilees 10:1-5:"In the third week of that jubilee the polluted demons began to lead astray the children of Noah's sons and to lead them to folly and to destroy them. And the sons of Noah came to Noah, their father, and they told him about the demons who were leading astray and blinding and killing his grandchildren. And he prayed before the Lord his God and he said, 'God of the spirits which are in all flesh, who has acted mercifully with me and saved me and my sons from the water of the Flood and did not let me perish as you did the children of perdition, because great was your grace upon me, and great was your mercy upon my soul. Let your grace be lifted up upon my sons and do not let the evil spirits rule over them, lest they destroy them from the earth. But bless me and my sons. And let us grow and increase and fill the earth. And you know that which your Watchers, the fathers of these spirits, did in my days and also these spirits who are alive' ".
Justin Martyr, 2 Apology 5: "The angels transgressed their appointment and were captivated by love of women, and begat children who are those that are called demons....Whence also the poets and mythologists, not knowing that it was the angels and those demons who had been begotten by them that did these things to men, and women, and cities, and nations, which they related, ascribed them to god himself, and to those who were accounted to be his very offspring, and to the offspring of those who were called his brothers, Neptune and Pluto, and to the children again of these their offspring".
Athenagoras, Legatio 24-25: "These [angels] fell into impure love of virgins, and were subjugated by the flesh, and he became negligent and wicked in the management of the things entrusted to him. Of these lovers of virgins, therefore, were begotten those who are called giants.... The souls of the giants, which are the demons who wander about the world, perform actions similar to the natures they have received".
Lactantius, Divinae Institutiones 2.15: "Thus from angels the Devil makes them to become his satellites and attendants. But they who were born from these, because they were neither angels nor men, but bearing a kind of mixed nature, were not admitted into Hell, as their fathers were not into heaven. Thus there came to be two kinds of demons; one of heaven, the other of the earth. The latter are the wicked spirits, the authors of all the evils which are done, and the same Devil is their prince....These contaminated and abandoned spirits, as I say, wander over the whole earth, and contrive a solace for their own perdition by the destruction of men. Therefore they fill every place with snares, deceits, frauds, and errors; for they cling to individuals, and occupy whole houses from door to door".
Commodianus, Instructiones 3: "The Almighty God, to beautify the nature of the world, willed that that earth should be visited by angels. But when they were sent down they despised his laws. Such was the beauty of women that it turned them aside. And being contaminated, they could not return to heaven. As rebels from God, they uttered words against him. Then the Most High uttered his judgment against them and from their seed giants are said to have been born. They made arts known to those in the earth, and they taught the dying of wool and everything which is done, and when they had died men erected images to honor them. But the Almighty, because they were of an evil seed, did not approve that they should be brought back from death when they died. So now they wander to subvert many bodies, and it is such as these especially that you this day worship and pray to them as gods".
Pseudo-Clementine Homilies 8.10-20: "But from their unhallowed intercourse spurious men sprang, much greater in stature than ordinary men, whom they afterwards called giants....When irrational animals fell short, these bastard men tasted also human flesh. For it was not a long step to the consumption of flesh like their own, having first tasted it in other forms. But by the shedding of much blood, the pure air being defiled with impure vapour, and sickening those who breathed it, rendered them liable to diseases, so that thenceforth men died prematurely. But the earth being by these means greatly defiled, these first teemed with poison-darting and deadly creatures. All things, therefore, going from bad to worse, on account of these brutal demons, God wished to cast them away like an evil leaven, lest each generation from a wicked seed, being like to that before it, and equally impious, should empty the world to come of saved men. And for this purpose, having warned a certain righteous man, with his three sons, together with their wives and their children, to save themselves in an ark, he sent a deluge of water, that all being destroyed, the purified world might be handed over to him who was saved in the ark, in order to a second beginning of life. And thus it came to pass. Since, therefore, the souls of the deceased giants were greater than human souls, inasmuch as they also excelled their bodies, they, as being a new race, were called also by a new name. And to those who survived in the world a law was prescribed of God through an angel, how they should live. For being bastards in race, of the fire of angels and the blood of women, and therefore liable to desire a certain race of their own, they were anticipated by a certain righteous law. For a certain angel was sent to them by God, declaring to them his will, and saying: 'These things seem good to the all-seeing God, that you lord it over no man; that you trouble no one, unless any one of his own accord subject himself to you, worshipping you, and sacrificing and pouring libations, and partaking of your table, or accomplishing aught else that they ought not, or shedding blood, or tasting dead flesh, or filling themselves with that which is torn of beasts, or that which is cut, or that which is strangled, or aught else that is unclean.' .... But you are still ignorant of this law, that every one who worships demons, or sacrifices to them, or partakes with them of their table, shall become subject to them and receive all punishment from them, as being under wicked lords. ... You ought to know that the demons have no power over anyone, unless first he be their table-companion; since not even their chief can do anything contrary to the law imposed upon them by God, wherefore he has no power over any one who does not worship him".