Pendragon (British) or Pen Draig (Celtic) is of English lore, meaning "head or chief dragon," and is referred to several individuals: Ambrosius Aurelianus, Uther, King Arthur and Maelgwn Gwynedd.
In Robert de Boron's Merlin, Uther's elder brother Ambrosius name is "Pendragon" and Uther's name becomes "Uterpendragon" after his brother death. In Alfred Tennyson's poem Lancelot and Elaine, it is Arthur's title rather than surname.
"Origin: England. A dragon whose name means 'giant dragon.' A giant beast that slumbers in the earth. This is the title given to the Celtic Kings. King Arthur's father, Uther, was called Pendragon as well."
—Shin Megami Tensei A-Mode DDS Dictionary
Shin Megami Tensei IV Apocalypse
"The kind of dragons from Arthurian lore. Its name means both "dragon's head" and "head dragon." When Arthur's father Uther fought the Saxons, two comets like fire soared across the sky. To commemorate this, he called himself Uther Pendragon, a name which Arthur inherited. Thus, a Pendragon is thought to be the symbol of a king's ultimate authority. Its figure can be seen in places such as the emblem on the shields of British knights."
—Shin Megami Tensei IV Apocalypse compendium
Pendragon can teach Nanashi the Titanomachia, Acid Breath and Charge skills through its Demon Whisper. It benefits from learning Physical, Ice, support and Electricity skills.
Devil Survivor 2
"The king of dragons from Arthurian lore. Its name means both "dragon's head" and "head dragon". When Arthur's father Uther fought the Saxons, two comets like fire soared the sky. To commemorate this, he called himself Uther Pendragon, a name which Arthur inherited. Thus, a Pendragon is thought to be the symbol of a king`s ultimate authority. Its figure can be seen in places such as the emblem on the shields of British knights."
