Arthur Eld was the ancient King and the greatest mythical hero of All-world, the Mid-World version of the legendary King Arthur. He is the only person before or since to have united the entire world after the Great Cataclysm, which destroyed the society of the Great Old Ones. Armed with Excalibur, a long sword taken from the legendary Kashamin Pyramid, the Eld united the people of Mid-World and led them to battle against harriers and mutants. After his victory, Arthur Eld crowned to be the King of All-World, and he pledged his loyality to the White and the Dark Tower, the magical axis point of the multiverse. His crown held thirteen different coloured gems, each one a striation in the Dark Tower's central oriel window. According to the legend, refused by many, some creatures from the Prim, led by the demonic magician, Maerlyn also appeared at the celebration as uninvited guests, offering thirteen seeing spheres to the High king as gifts. However they revealed their true nature, as they started to feast on the members of Arthur's court. Arthur himself survived the incident, but unwittingly impreganted one of the creatures, the Crimson Queen with his bastard son, the were-spider Crimson King. After his own wife, Queen Rowena become barren, Arthur desperately wanted to give a male, human heir to his kingdom. To do so, he took over forty mistresses, known as "gillies" or "jillies", but his only son born to Emmanuelle, the daughter of his advisor, Sir Kay Deschain (who died protecting him from the Crimson Queen). Thus the line of Deschain also posessed the hereditary title as the Line of Eld, and the Lord of Gilead, Arthur's capital. According to the legend, the inherited guns of Deschain were made from the blue steel of the melted Excalibur, while others said them to be gifts from the Dark Tower itself, or weapons also taken from the Kashamin Pyramid. Arthur also passed down to his human descendants his horn, known as the Horn of Eld, also said to be a magical aftifact.
He banned the human sacrifices of the Reaptide Festival, which was founded by Maerlyn, though it carried it on regardless. As compromise, he deemed one person in all of All-World would be sacrificed at the Ghostwood/Charyou Tree each years. Ultimately, his gilly Emmanuelle would burn on a Charyou tree and his wife would give birth to a Were-Spider who would kill her and be killed in turn.
In the months afterward, a ghost-like apparition of Rowena began to wander the halls and grounds of the castle. Arthur, stricken by the guilt of forsaking his wife which contributed to her death, followed the apparition into the woods and through a doorway which lead to a dogan, a place where magic and technology fused in order to create lethal weapons, and where he was captured and held for months. His form and memories were used to create an army of undead golems that terrorized New Canaan nightly for months. Ultimately, he was rescued by his knights, Sir Alfred Johns and Sir Bertrand Allgood with the assistance of the Guardians of The Beam.
During the twelfth year of his reign Arthur is known to have killed the snake-ike creature Saita. It was this that made him realize his knights also needed guns and so he set up the barony of Hendrickson at the foot of The Shaved Mountains to supply firearms. A second enterprise, Hemphill was also created in order to reduce the number of mutant stock in the kingdom.
In total, Arthur Eld ruled All-World for seventy years, after his death the kingdom remained unified, although it fragmented into a loose network of independent baronies.
It is rumored that only someone who carries Excalibur or another sign from Arthur Eld may enter the Dark Tower.