Origin
Enemy of the Spectre. One of the Seven Unknown Men, the being who would become Zor was tasked with protecting and maintaining the continuity and vibrancy of the multiverse. Separating from his fellows, he became determined to shape the world as he saw fit, destroying that which he saw as childish. To this end he wove the menace of the Sheeda into continuity, and set them to invade the present day, though it had not yet reached the utopian state the Sheeda typically prey upon.
Creation
Zor was created by Jerry Siegel and Bernard Baily. He made his first appearance in More Fun Comics #55. The character was significantly rebooted by Grant Morrison.
Character Evolution
Golden Age
In the Golden Age, Zor was a magician of unknown provenance who possessed vast mystical powers. He described himself as a spirit who had wandered the Earth for centuries, causing evil.
Modern Age
The Modern Age introduced the current version of Zor, recreating him completely as a metatextual entity. It is unclear if he simply assumed the identity of Zor in the present time, and is therefore a facsimile or body thief, or if he lived through Zor's publication history, and is thus the original, actual Zor; dialogue implies the latter is the case. This would suggest that his Golden Age exploits remain canon, though his motivations for his actions then are unclear. Zatanna said that he is omnipotent. Zor still remembers all of his battles that he had against Spectre in the Golden Age.
Major Story Arcs
Spectre
Zor reveals himself to the Spectre, and the pair battle briefly, with Zor gaining the upper hand before abruptly vanishing. Disguising himself as Jim Corrigan he abducts Clarice Winston and takes her into an alternate dimension, where he attempts to entrap her. The Spectre tracks him down and tricks Zor into snaring himself in a paralysis beam. He manages to contact a scientist telepathically, and convinces him to free him from the beam. Seeking revenge on the Spectre, he frames Corrigan for murder. Easily besting the Spectre in combat, he rescues a condemned murderer from being executed and sends him to kidnap Clarice. He traps the Spectre, intending him to witness Clarice's death. Spectre manages to escape and construct a casket out of ectobane, a substance to which evil spirits such as Zor have a weakness. Zor is entrapped in the casket and thrown over a waterfall.
Seven Soldiers of Victory
Plotting with the Sheeda in Slaughter Swamp, Zor is encountered by the Newsboy Army. He sews each of them a suit of clothing that corrupts their character arcs, causing the team to darken and ultimately fall apart in scandal. His actions are unknown in the intervening decades. In the present day, he encounters Zatanna as she enters Slaughter Swamp seeking the Unknown Men. The pair conduct a magical battle within their minds. Zor successfully breaks Zatanna's Merlin, and attempts to absorb the comic book universe into himself. He is subdued by Zatanna, and taken into the custody of the Seven Unknown Men. One of the Seven stitches him into a miser's coat, enmeshing him into the story of Cyrus Gold. He sends Zor-as-Gold out into Slaughter Swamp just in time for him to be found and murdered by the townsfolk, thus creating Solomon Grundy.
Powers and Abilities
As an Unknown Man, Zor technically exists outside the narrative, and so is theoretically omnipotent while in the story. He is a reality warper, able to cause anything he wishes to occur; this often manifests itself as something resembling magic. Though he possesses cosmic awareness and is aware of the fourth wall.
Weapons and Equipment
Zor possesses a time-sewing machine with which he can sew suits for characters to wear, thus dictating the courses of their character arcs. It can also be used to sew up holes in time.