Arthur refers to the heroic legendary king of Britain, the original wielder of the sword Excalibur( not in Nethack however)
His legend probably originates from a real historical figure of Roman Britain. From that forgotten historical figure, the mythology was gradually fleshed out over centuries.
Ector took both his sons to the church before which the
anvil had been placed. There, standing before the anvil, he
commanded Kay: "Put the sword back into the steel if you
really think the throne is yours!" But the sword glanced
off the steel. "Now it is your turn", Ector said facing
The young man lifted the sword and thrust with both arms; the
blade whizzed through the air with a flash and drilled the
metal as if it were mere butter. Ector and Kay dropped to
their knees before Arthur.
"Why, father and brother, do you bow before me?", Arthur asked
with wonder in his voice.
"Because now I know for sure that you are the king, not only
by birth but also by law", Ector said. "You are no son of
mine nor are you Kay's brother. Immediately after your birth,
Merlin the Wise brought you to me to be raised safely. And
though it was me that named you Arthur when you were baptized,
you are really the son of brave king Uther Pendragon and queen
And after these words, the lord rose and went to see the arch-
bishop to impart to him what had passed.
Emanuel Frynta, and Vackav Cibula ]