Reading the ambitious "inspirational reading" list at Huge Ruined Pile led me to believe that an "Appendix Nu" would be a useful addition to the canon. Appendix Nu would include the body of myth, legendry, historical narratives, and early works of fiction that inspired modern fantastists. The assembly of Appendix Nu would have to be a group effort in order to close any lacunae that would inevitably result from our cultural biases (I am not using this term pejoratively- my own biases are toward Greek and Roman legends, Norse Sagas, Irish and Welsh legends, and the picaresque tales of the Iberian peninsula- with a passing familiarity of the epics of India and some of the Mesoamerican material).
Skapti the priest, Thorarin's son, a wise man, was there at the time. He took then the skull of Egil, and set it on the churchyard fence. The skull was wondrous large, but still more out of the common way was its heaviness. It was all wave-marked on the surface like a shell. Skapti then wished to try the thickness of the skull. He took a good-sized hand-axe, and brandishing it aloft in one hand, brought down the back of it with force on the skull to break it. But where the blow fell the bone whitened, but neither was dinted nor cracked. Whence it might be gathered that this skull could not easily be harmed by the blows of weak men while skin and flesh were on it.