I hope this is what you are looking for on a more esoteric level.
The Zohar explains that the mixed multitude, also known as the "Erev Rav", consists of the "fallen ones" for example. These are the Nephilim.
There are five groups in the mixed multitude. These are the Nefilim (fallen), the Giborim (mighty), the Anakim (giants), the Refaim (shades) and the Amalekites. Because of them, the small Hei fell from its place (Binah).
The Akeidat Yitzchak explains the following:
The reference to the nephilim is (a) to insure that the men described as "sons of G-d" are not confused with beings that have been sired by G-d; (b) to account for the fact that we find some descendants of the generation of the deluge having survived till the era of Moses, such as the giant Og, for instance. These people encountered by Israel in the desert some 700 years later were understandably viewed as "sons of G-d" by dint of their genealogy. "When G-d saw that the evil perpetrated by man on the earth was great, and that all his thought processes were evil all day long, He regretted that He had made man" (Genesis 6,5-6). Philosophers distinguish between evil as merely an act, and evil which had been both planned and executed. The person who commits the former can reform easily, since his thought processes have remained unaffected and can be employed to help control his actions. Not so when the evil is the product of one's thought processes. What counterweight is there then for such a person to achieve rehabilitation? It is this latter evil G-d encountered in man, and which the verse in question comments upon.
The Targum Yonatan on Genesis 6:4 explains what "these fallen ones" were, or "who they were":
Schamchazai and Uzziel, who fell from heaven, were on the earth in those days; and also, after the sons of the Great had gone in with the daughters of men, they bare to them: and these are they who are called men who are of the world, men of names.
In the book of Enoch (chapter 6) it says:
And it came to pass when the children of men had multiplied that in those days were born unto them beautiful and comely daughters. 2. And the angels, the children of the heaven, saw and lusted after them, and said to one another: 'Come, let us choose us wives from among the children of men and beget us children.' 3. And Semjâzâ, who was their leader, said unto them: 'I fear ye will not indeed agree to do this deed, and I alone shall have to pay the penalty of a great sin.' 4. And they all answered
Rashi says that the nefilim were princely angels who came as messengers from G-d. What happened to them?
They, too, intermingled with them (the daughters of men).
See also the Ibn Ezra:
THE SONS OF G-D. The term bene Elohim (the sons of g-d) refers to the
sons of the judges who dispensed G-d’s (Elohim) justice.1 Others say
that Elohim refers to G-d Himself and the sons of G-d are holy ones
(saints) living on earth. They are called sons of G-d in the sense of
Ye are the children of the L-rd your G-d (Deut. 14:1). Others say that
the sons of G-d refers to the children of Seth2 and that the daughters
of man refers to women of Cain’s family.3 However, it appears to me
that the sons of G-d refers to those who know the will of the most
High. These men chose women who matched them astrologically and
physically. Hence they produced mighty men. It is possible that they
took women even against their will.4
The Zohar then goes on to explain the difference between the nefilim:
Bereshit A: Verse 466 (translation taken from here)
Rabbi Yehuda said: Even those Nefilim, WHO ARE THE CHILDREN OF AZA, AZAEL AND NA'AMAH are called THE SONS OF ELOHIM. The words: "The same were mighty men" (Ibid.) INDICATE THAT ONLY THEY WERE THE MIGHTY MEN AND NOT THE ORIGINAL NEFILIM. There were only 60 of them by supernal reckoning, AS COMPARED WITH THE SIX DIRECTIONS - NAMELY CHESED, GVURAH, TIFERET, NETZACH, HOD AND YESOD OF ZEIR ANPIN. WE CAN DRAW ANALOGY FROM THE VERSES. Here in the scripture, it is written: "The same were mighty men" and there - IN RELATION TO KING SOLOMON, WHO IS ZEIR ANPIN - it is written, "Sixty valiant men are round about it" (Shir Hashirim 3:7). JUST AS THEY ARE 60 THERE, SO HERE THEY ARE 60, YET THE FIRST ONES ARE DRAWN FROM ABOVE, FROM SIX SIDES OF ZEIR ANPIN. Rabbi Yosi continued by saying: "The same were the mighty men of old (lit. 'from the world')" and this is written precisely TO DISTINGUISH THEM FROM THE FIRST NEFILIM, AZA AND AZAEL, WHO ORIGINATED IN THE WORLD ABOVE. THE WORLD IS THE FEMALE PRINCIPLE OF ZEIR ANPIN AND THE TEXT TEACHES US THAT THOSE MIGHTY MEN WERE INTENDED TO BECOME A CHARIOT FOR THE MALE AND FEMALE PRINCIPLES, AND THUS A PART OF THE FEMALE CALLED THE WORLD. HE ASKS: To which name does the text refer when it is written: "Men of renown (lit. 'name')" (Beresheet 6:4)? This is the world we have mentioned, WHICH IS THE FEMALE PRINCIPLE. The phrase "men of name" is precise. IT TEACHES US THROUGH AN ANALOGY BY STATING THAT it is written here: "men of name" and in another place: "when he blasphemes the name" (Vayikra 24:16). It is written: "And the son of the Yisraelite woman blasphemed the name" (Ibid. 11). JUST AS NAME IMPLIES THE FEMALE PRINCIPLE IN THE PREVIOUS VERSE, SO IT IMPLIES THE FEMALE PRINCIPLE IN THIS VERSE.