Kabbalah zu Bereschit 41:34

About the Nefilim (the fallen ones), it is written: "That the sons of the Elohim saw that the daughters of men were fair" (Beresheet 6:2). These are the second group (of the erev rav, emanating from the Chochmah of the Kelipot) from those fallen from above, (from Aza and Azael, who were angels above. Hashem dropped them out of the heavens). When the Holy One, blessed be He, desired to create man, he said (to the angels) "Let us make man in our image..." (Beresheet 1:26). He wanted to make him a leader over all (the angels above), so that he might govern all (the angels) and they would be under his rule, as is written about Joseph: "And let him appoint officers over the land" (Beresheet 41:34).