My favourite is the legend of King Arthur and the Knights of the Round Table.
There is of course some debate about the historical accuracy of the Arthurian legends and it's one of those legends that has been added to and embellished over the centuries.
Some historians claim that the legend is based on a real tribal leader named Arthur, others maintain that the whole legend is just a story and King Arthur never actually existed.
This does not stop many English people, especially in Somerset, from believing that that he was a real historical figure. nor did it stop the monks of Glastonbury Abbey from announcing that they had found his tomb.
I've even visited the site of it in the remains of Glastonbury Abbey.