Hello Rabbi, I want to know what is the position of Mainstream Judaism on the identity of the Nephilim? I personally believe they were humans but some people tend to see them as hybrids or heroes. Thank you

Shalom, Thank you for your question. You are referring to the verses in Berashit 6, 4 and Bamidbar 13, 33. In Berashit the Torah writes “1 And it came to pass, when men began to multiply on the face of the earth, and daughters were born unto them, 2 that the sons of God saw the daughters of men that they were fair; and they took them wives, whomsoever they chose. 3 And the LORD said: 'My spirit shall not abide in man for ever, for that he also is flesh; therefore shall his days be a hundred and twenty years.' 4 The Nephilim were in the earth in those days, and also after that, when the sons of God came in unto the daughters of men, and they bore children to them; the same were the mighty men that were of old, the men of renown.” In Bamidbar it writes about the spies report on the land of Israel “33 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.'”. There are many different opinions as to who or what these “nephilim” are. One of the classic medievil commentators (the Tur) sums up the opinions as follows “ "the Nephilim were on earth at that time." According to Rashi these creatures had fallen from heaven (in disgrace) and had in turn caused people on earth to fall from their spiritual level to a spiritually still lower level [the hebrew root of nephil means to fall]. The name Nephilim corresponds to the Hebrew word Anakim, "giants." At any rate, ordinary people were frightened of these "giants." Other commentators simply understand the term Nephilim as representing human beings who, due to their imposing stature, made everyone fall down before them in a state of fear. Rabbi Joseph Kimchi explains the word Nephilim as meaning "great men, giants." He quotes Job 14,18 as a parallel, i.e. that even the most powerful and great phenomena (such a tall mountains) on earth will ultimately fall, collapse.” Another commentator (Shadal - Samuele Davide Luzzatto 1800 – 1865) writes “The giants (ha-nefilim) – We know that the nefilim were tall from Numbers 13:33, "And there we saw the Nefilim, the giant race, of the Nefilim; and we seemed to our own eyes as so many grasshoppers, and so we must have seemed to their eyes". This verse also shows that there were nefilim after the Flood, and so, in my opinion, the phrase "and also afterwards" is connected with the preceding phrase. After the Flood, too, when society was reorganizing, there were tall, wild men who kept company with the daughters of society. ... The existence of a few giants or abnormally tall men cannot be denied: Moses mentions Og, [Joshua's] spies mention Ahiman, Sheshai, and Talmai; in Samuel we find Goliath and others. Besides the testimony of the Bible, we now see bones of elephants and other [ancient] animals in the bowels of the earth, and scholars say that the animals to which these bones belonged were as large as elephants. It may well be that besides those animals which have been discovered up to now, some human beings as large as "elephants," from our point of view, will be found as well. So, according to the more “simple” reading of the text, they were giant men. But, as we saw in Rashi, there is a Rabinic Midrashic explination that equates them with some type of fallen angels. I believe it would be correct to say that “mainstream Judaism” explains the term to refer to giant men – although that does not reject a possible explanation (on a Midrash level) referring to spiritual matter of fallen spiritual beings. Blessings.