Who were the "giants" mentioned in Genesis 6:4 in the King James Version?  The word "giants" in the KJV is "Nephilim" and is an archaic word, the meaning of which has been lost.  As a result, various Bible translations translate the word meaning as "large" "mighty" "great" or "fallen."  The essentials of the Nephilim story is they were angels in Heaven who saw human women, lusted after than, left Heaven and had human women as wives.  This was regarded as highly improper.  The story of the Nephilim is a fascinating, but little known story of the Bible.