King Arthur's knights, gathered at the Round Table to celebrate Pentecost, see a vision of the Holy Grail.

T. S. Eliot and the Holy Grail

The Nobel Laureate drew on a centuries-old legend when he put the Fisher King in The Waste Land.
King Arthur removing the sword from the stone

The Return of the Hidden Hero

The hero/king/god isn’t dead, he’s just sleeping, often under a mountain, waiting for the day his people really need him. 
King Arthur Harry Potter

Harry Potter, the Arthurian Romance

Perhaps the Harry Potter stories are so potent because they rework the iconic hero stories of medieval French Arthurian romances.