The Nephilim (נפילים) were offspring of the “sons of God” and the “daughters of men” before the Deluge according to Genesis 6:4; the name is also used in reference to giants who inhabited Canaan at the time of the Israelite conquest of Canaan in Numbers 13:33. The story of the nephilim is further elaborated in the Book of Enoch, where the Greek, Aramaic, and main Ge'ez manuscripts of 1 Enoch and Jubilees connect the origin of the nephilim with the fallen angels
The Nephilim, (Fallen Angels, Giants and the Watchers) The Bible speaks of God regretting that he had even made man when he saw what Satan did. He turned many angels against Jehovah. They materialized human bodies to have sex with beautiful women. And the earth came to be ruined in Jehovah's sight. Satan's challenges against God had to be addressed.