In the book I Enoch, a commonly used name for the fallen angels (the sons of God) is the Watchers. Another term used by many of the ancients for the fallen ones is the Gibborim. The following, however, are the Biblical terms for the giants:
1)Nephilim- These are the antediluvian (pre flood) giants. The term means fallen ones. Archaeologists in North America believe they located possible Nephilim bones and remains, highlighted by two rows of teeth and heights exceeding eight and even nine feet. These giants were the result of the fall depicted in Genesis 6:1-4, whereby the sons of God (sons of heaven, fallen angels) took wives for themselves among whom they chose. The Nephilim apparently settled throughout the world prior to the great deluge of Noah.
2)Rephaim- These are the giants after the flood. They include King Og, Goliath and his brothers, and many others. They seem to be confined more so to the land of Canaan and surrounding nations, whereas the Nephilim settled globally. Moses confronted giants as the Israelites journeyed towards the land of Canaan. The Anakim giants were encountered by Moses on the way to Canaan and they are another group of the post flood Rephaim giants. All of the Canaanite tribes had giants among them and were also part of the Rephaim. The twelve spies encountered the giants when they spied out the land and felt like grasshoppers in their presence. Giants are mentioned throughout the Bible much more than most readers realize.
Many conservative theologians throughout history, have thought there was a great spiritual fall involving angelic beings, and they “left their first estate,” thusly intervening in the affairs of men, and taking wives for themselves prior to the flood. There was a spiritual fall both before and after the flood. Mount Hermon is the place that ancient writings tell us the fallen angels gathered at. We do not know exactly how this happened since it was a supernatural act. Here is something you may have never thought of. Most people equate the demons who plague our earth as fallen angels, BUT the Bible says that the fallen angels who left their proper domain and abode (Jude 6) are already locked in everlasting chains until the final judgment. So how could they become the demons who currently inhabit our world? Another possibility is that the demons who wander the earth came from the giants who were the progeny of the sons of God. It is interesting to think about. There will be one more part for this series on the Biblical giants. The hybrids throughout the ancient world will be examined. It is fascinating to realize that there is indeed fact (distorted over the centuries) behind the ancient myths that we are all familiar with.