Nifillum

The Nifillum (spelling?) were said to be in excess of 9ft tall, and the product of the mingling of the Angels and human females. Goliath, who was felled by David, was supposedly the last of their kind. The engineers (at least the ones depicted in the film) could be Angels of lore... the ones on LV223 part of the "fallen ones"... jealous of their creator's other creation... us.