King Arthur

Arthur as Giant and Giant killer in Wales

Arthur is a folkloric hero in these materials, a peerless warrior of giant-like stature who leads a band of superhuman heroes that roam the wild places of the landscape (their presence there being evidenced by various remarkable features in those regions), who raids the Otherworld whilst being intimately associated with it, who fights and protects Britain from supernatural enemies, who hunts wondrous animals and who takes part in mythical battles

Arthur himself was probably not originally a historical figure but rather a folkloric, heroic one; 'the leader of a band of heroes who live outside society, whose main world is one of magical animals, giants, and other wonderful happenings, located in the wild parts of the landscape'

Cei with his magical attributes, his heroic characteristics and his superhuman powers would fit very well into such a folkloric cycle and, indeed, his ability to change his height -- and other traditions which make it clear that Cei was thought to be a giant -- is strongly reminiscent of folkloric suggestions that Arthur and his relatives were giants/could alter their height

a distinguishing feature of the earliest Arthurian material and, indeed, the 14 feet long grave is strongly reminiscent of the variable and great length of the grave of Arthur's son, Amr and the numerous references which suggest that Arthur and his chief companions were believed to have been giants . Professor Grooms in his The Giants of Wales, considers Gwalchmei to have been a giant and notes that he appears as such in local folklore.

The final resting place of the Holy Grail, meanwhile, is believed to be Castell Dinas Bran on the mountainside above Llangollen.

How Arthur killed Idris the Giant:

Giant Idris - The Commot of Ystymmer.
And Arthur killed him.
In the land of Merioneth in the parish of Dolgelly
is a mountain or peak or high large mount that is called Cader Idris.

And on the highest crown of this mountain is a bed-shaped form as it were, great in length and width, built of slabs or stones fixed around it. And this is called The Bed of Idris, though it is more likely that it is the grave in which Idris was buried in ages past. And it is said that whoever lies and sleeps on that bed, one of two things will happen to him, either he will be a poet of the best kind, or go entirely demented.

How Arthur killed Rhita the Giant:

And in the land of Merioneth also, in the parish of Llanelltyd and the commote of Ardudwy, and a little from the other hills and on the other side of the river that divides the commotes, is another hill called Moel Ysbryn, because Ysbryn Gawr had his dwelling there; from whose name the hill received its name. And all these giants were of enormous size, and in the time of Idris Gawr, which Idris was king and chief over them. And in the land of Merioneth also, and close to Pen Aran in Penllyn, and under the place called Bwlch y Groes, is a grave of great dimensions where they say Lytta or Ritta or Ricca or Rithonwy or Itto Gawr was buried; whose body some of the tribe of giants removed from Eryri to somewhere near Mynydd Arau Fawr in Penllyn. This Rica Gawr was the one whom Arthur had fought and had killed in Eryri. And this giant made this for himself, a robe of the beards of the kings he had killd. And he sent to Arthur to order him to cut off his own (i.e., Arthur's) beard and send it to him. And as Arthur was the chief of the Kings, he would place his beard above the other beards as an honor to Arthur. And if he would not do that, he begged Arthur to come and fight him; and the victorious of them to make a robe from the other's beard. And after they went to fight Arthur had the victory and he took the giant's beard and his robe. Rhitto Gawr said he never met a second man as brave as that giant.

And others relate the story thus, namely:
Rhitto Gawr, calling himself king of Gwynedd in the time of Arthur, sent to Arthur to ask him for his beard. And Arthur refused it to him. And on this they met on the top of a hil called Bwch y Groes between Mowddwy and Penllyn in the land of Merioneth. And in the meeting at Itto's wish, they cast their weapons away from them, to prove their strength. And at last by a struggle, and rolling, they came to the plain, to the place called Blaen Cynllwyd, after plucking each other's beards. And in remembrance of that, that hill is called Rhiw y Barfau. And after that, they fought with their swords, in the place where Arthur killed the giant: in which place is Rhitto's grave to be seen to this day at the foot of the slope.

snowdon

Legend also has it that the cairn at the top of Snowdon is the tomb of fearsome giant, Rhita Gawr.

the three hags and how Arthur did them to death:

And in the land of Aberteifi and in the parish of Llan Dyssul lived a giant and his name was Howel Gawr; and the place he lived in is still called Castell Howel Gawr.
And in the land of Aberteifi and in the parish of Llanfair or Llwyn was a giant called Llyphan Gawr, and the place he lived in is still called Castell Llyphan Gawr.
And in the land of Aberteifi and in the parish of Bangor lived Pyscoc Gawr; and the place he dwelt in is still called Castell Pyscoc Gawr.
Three hags were wives to the last three giants, namely, to Howel Gawr, and Llyphan Gawr, and Pyscoc Gawr; and those three giantesses were killed (they say) by Gwalchmai the nephew of Arthur by trickery, because they could not be destroyed except by cunning, on account of their strength and power. And three sisters were these three hags; and within the three castles they were killed, namely Castell Howell, Castell Llyphan, and Castell Pyscoc, according to what is related of them.

How Arthur rescued the brothers of Gwynhwfar:

In the land of Brycheiniog near to the town of Aber Hodni: Gogfran Gawr lived in Aber Ysgyr in the caer above the river. Gwenhwyfar the daughter of Gogyrfan Gawr was married to Arthur.

There was a place on the frontier of the land of Shropshire, called Bron Wrgan, and it was the abode of giants.
And in this place it is related that there were some brothers to Gwenhwyfar, the daughter of Gogyrfan Gawr, who were imprisoned by some of these giants. And she grieved greatly they were in captivity. But Arthur saved them each one, killing the giants, and taking the head of the biggest of them and throwing it into the middle of the river instead of a stone, in stepping across the river, to go to Castell y Cnwclas. And as he placed his foot on the head of the giant in stepping across the river Arthur said, Let the head grow in the river instead of a stone. And henceforth that river was called Afon Tyfed-iad, as the side of the giant's head grew.

How Maylor Gawr blew his horn Three Times

And in the country of Aberteifi, before the coming of Arthur to this island, there formerly lived Maylor Gawr, and the place where he lived is still called Castell Maylor which was built on a high hill or high ridge called Y Dinas on the one side of the river Ystwyth within the boundary of the town of Aber Yystwyth.
To this Maylor Gawr were three sons, namely, Cornippin Gawr, and Crygyn Gawr, and Bwba Gawr. Corpinnin Gawr dwelt in a castle which is still called after his own name, namely Castell Cornippin opposite the parish of Llan Ychaiarn within the commote of Meifienydd. And it came to pass that Maylor Gawr was taken prisoner in a place called Cyfeilog, about twelve miles from his own castle: and when on the point of being put to death, he begged of his enemies to permit him to blow his horn three times before suffering death, which thing was allowed to him. And then he blew his horn the first time until the hair on his head and beard fell. And on the second blast of his horn, so great was the strength and force of the sounding that all his finger and toe-nails fell off completely. And on the third blast of his horn the intensity of the force of the sound caused the horn to be broken into small pieces. And then when his son Cornippin was hunting, as he rode on his huge horse and leading his hound by hand, and hearing the sound of his father's horn, he saddened greatly, and he longed beyond measure for his father: and that place, to this present day, is called Cefn Hiraethog. And then he began to return towards his father in seeking to help him: and in riding with such haste and swiftness, he tore the head of his hound off its body, until there only remained in the leash the head and mouth of the dog. And that place is still called to this day, The Pass of the Dog's Muzzle. And when he saw that, he spurred his steed until the horse leapt at one bound over the Ystwyth River so that it was a great wonder to see such a length of leap, is called to this hour Ol Carn y March. And in that manner Cornippin came up to his father, where after fighting he also was killed.

These giants lived in Wales before Arthur came to this island, and their custom while they lived was to kill whatever men should come to lodge within their strongholds until at last the same man came and killed them both the same night by cunning.

Arthur kills three sisters of Cwibr Gawr:

In the country of Morgannwg was Cribwr Grawr in Castell Cefn Cribwr by Llan Gewydd. Arthur killed three sisters of Cribwr by treachery. Because Arthur nicknamed himself Hot Pottage to the first sister, and Warm Porridge to the second sister (so the tale runs), and a Morsel of Bread to the third, and when the first sister called for help against Hot Pottage Cribwr answered: Wench, let him cool; and in the same manner he answered the second sister, when she sought assistance against Warm Porridge. And the third sister called out that the Morsel of Bread was choking her; and to this he answered, Wench, take a smaller piece. And when Cribwr reproached Arthur for killing his sisters

Arthur replied by an englyn in this manner;

Cribwr take thy combs
And cease with currish anger (churlish?)
If I get a real chance—surely
What they have had, thou shalt have too.

No one could kill the three sisters together, so great was their strength, but singly by stealth Arthur killed them. Later he killed Cribr Gawr in open combat.
And the place is still called after his name Cribarth, namely, Garth Cribwr Gawr. And opposite to him was another giant called Oyle Gawr, and his dwelling place is still called Pen Oyle.
And in the same parish in a place still called Ynys Cedwyn there was another giant called Cedwyn Gawr, and these three lived in Arthur's time. And the first two were killed by Arthur.

Arthur kills another couple of Giants:

And in the parish of Pen Ederyn, Dynas Gawr was killed by Arthur. And the place where he dwelt is still called Caer Craig Dynas Gawr, at other times Craig y Llyn.

Ceimiad Gawr has a grave in the soil of Dyffryn Mochnant in a place called Llwyn y Meini Hirion near Nant Ceimiad, in the parish of Pennant Mylangell, where he was killed (so they say) by Arthur, and two long stones mark the length of the grave, one at each end.

freely excerpted and adapted from Sion Dafydd Rhys, ca. 1600
Peniarth MS 118 f.829-837 and other sources.