Was Satan Behind Genesis 6?

"I will put hostility between you and the woman, and between your offspring and her offspring. He will bruise your head, and you will bruise his heel" (Genesis 3:14-15). Eden names a single hostile figure and promises his ultimate defeat — but nowhere does the text go on to say that this same figure personally orchestrated the very different rebellion that follows two chapters later.
Honesty about the text requires an honest answer here rather than a confident one either way. There is no verse anywhere in Scripture that directly states the serpent of Eden was behind the sons of God rebellion of Genesis 6. The two episodes are best treated as related but textually distinct instances of supernatural rebellion — two separate outbreaks of the same underlying pattern of creaturely revolt against Creator, rather than a single conspiracy directed by one mastermind across both. Later Jewish tradition does occasionally connect the two, sometimes naming a lead figure of the Genesis 6 rebellion by a name distinct from the serpent of Eden altogether — but that connection remains outside the explicit claims of the biblical text itself, which simply does not say. Resisting the urge to manufacture certainty the text withholds is itself a form of faithfulness to what has actually been revealed.
What the text does say plainly is the result: "The Nephilim were in the earth in those days... Those were the mighty men who were of old, men of renown" (Genesis 6:4). Whether one hostile will lay behind both Eden and the flood generation or two separate rebellions simply multiplied the same corruption, Scripture's verdict on both is identical — real, tragic, creaturely revolt, and neither one ever outside the sovereignty that will finally answer it.