The Nephilim were in the earth in those days, and also after that, when the sons of God came unto the daughters of men, and they bare children to them: the same were the mighty men that were of old, the men of renown. (Genesis 6:4)
The land, through which we have gone to spy it out, is a land that eateth up the inhabitants thereof; and all the people that we saw in it are men of great stature.
And there we saw the Nephilim, the sons of Anak, who come of the Nephilim: and we were in our own sight as grasshoppers, and so we were in their sight. (Numbers 13)
Now I desire to put you in remembrance, though ye know all things once for all, that the Lord, having saved a people out of the land of Egypt, afterward destroyed them that believed not.
And angels that kept not their own principality, but left their proper habitation, he hath kept in everlasting bonds under darkness unto the judgment of the great day. (Jude 1:6)
....he went and preached unto the spirits in prison, that aforetime were disobedient, when the long suffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls, were saved through water... (1 Peter 3:20)
....as were the days of Noah, so shall be the coming of the Son of man. (Matthew 24:37)