Genesis 6:4
2 the sons of God saw that the daughters of humankind were beautiful. Thus they took wives for themselves from any they chose. 3 So the Lord said, “My Spirit will not remain in humankind indefinitely, since they are mortal. They will remain for 120 more years.” 4 The Nephilim were on the earth in those days (and also after this) when the sons of God would sleep with the daughters of humankind, who gave birth to their children. They were the mighty heroes of old, the famous men. 5 But the Lord saw that the wickedness of humankind had become great on the earth. Every inclination of the thoughts of their minds was only evil all the time. 6 The Lord regretted that he had made humankind on the earth, and he was highly offended.
Deuteronomy 3:11
9 (the Sidonians call Hermon Sirion and the Amorites call it Senir), 10 all the cities of the plateau, all of Gilead and Bashan as far as Salecah and Edrei, cities of the kingdom of Og in Bashan. 11 Only King Og of Bashan was left of the remaining Rephaites. (It is noteworthy that his sarcophagus was made of iron. Does it not, indeed, still remain in Rabbath of the Ammonites? It is 13½ feet long and 6 feet wide according to standard measure.) 12 This is the land we brought under our control at that time: The territory extending from Aroer by the Wadi Arnon and half the Gilead hill country with its cities I gave to the Reubenites and Gadites. 13 The rest of Gilead and all of Bashan, the kingdom of Og, I gave to half the tribe of Manasseh. (All the region of Argob, that is, all Bashan, is called the land of Rephaim.
Notes and References
"... The specific correlation between the Nephilim in Numbers 13:33 and “the sons of Anak” (verses 22, 28) would have widened the horizon for ancient readers to have inferred links between groups of various names within the biblical tradition, whether in the Masoretic text or the LXX tradition. For example, in Deuteronomy 2:10–11 an apparent gloss refers to inhabitants of Ar called “the Emim … a great and numerous and tall people” who “like the Anakim are thought to be the Rephaim” (see also verses 20–21). The correspondence chain of Giborim = Nephilim = Anakim = Rephaim, which could be inferred from reading synthetically the Hebrew of Genesis 6, Numbers 13, and Deuteronomy 2, is consistent with a translation strategy in the Greek tradition that often applied, as we have seen above, the term γίγας ('giants'), for these words. By implication, Og king of Bashan could have been related to this circle, as may be suggested by the gloss at Deuteronomy 3:11 (see also 3:13) about the unusually large size of his bed and the claim that he “alone was left remaining from the remnant of the Rephaim (מיתררפאים)” ..."
Stuckenbruck, Loren T. The Myth of Rebellious Angels: Studies in Second Temple Judaism and New Testament Texts (p. 6) Mohr Siebeck, 2014