For thus they allured the Watchers who were before the flood; for as these continually beheld them, they lusted after them, and they conceived the act in their mind; for they changed themselves into the shape of men, and appeared to them when they were with their husbands.
And the women lusting in their minds after their forms, gave birth to giants, for the Watchers appeared to them as reaching even unto heaven. Reuben 2:18&19
In the days of Jared, two hundred Watchers descended on Ardis, the summit of Mount Hermon. On this mountain the Watchers swore an oath and bound themselves to it. Book of Jared, Dead Sea Scrolls, 1947
Make ye mention to the nations; behold, publish against Jerusalem, that watchers come from a far country, and give out their voice against the cities of Judah. Jeremiah 4:16
I saw in the visions of my head upon my bed, and, behold, a watcher and an holy one came down from heaven;
This matter is by the decree of the watchers, and the demand by the word of the holy ones: to the intent that the living may know that the most High ruleth in the kingdom of men, and giveth it to whomsoever he will, and setteth up over it the basest of men.
And whereas the king saw a watcher and an holy one coming down from heaven, and saying, Hew the tree down, and destroy it; yet leave the stump of the roots thereof in the earth, even with a band of iron and brass, in the tender grass of the field; and let it be wet with the dew of heaven, and let his portion be with the beasts of the field, till seven times pass over him; Daniel 4:13&17&23
And in the second week of the tenth jubilee Mahalalel took unto him to wife Dinah, the daughter of Barakiel the daughter of his father’s brother, and she bare him a son in the third week in the sixth year, and he called his name Jared, for in his days the angels of the Lord descended on the earth, those who are named the Watchers, that they should instruct the children of men, and that they should do judgment and uprightness on the earth. Book of Jubilees 4:15
And it came to pass when the children of men began to multiply on the face of the earth and daughters were born unto them, that the angels of God saw them on a certain year of this jubilee, that they were beautiful to look upon; and they took themselves wives of all whom they chose, and they bare unto them sons and they were giants. Book of Jubilees 5:1