J. Glegg (what the "J." stands for is unknown) was a powerful and wicked magician in the Land of Oz.
History
Glegg begs the enchanted Peg Amy to marry him.
He fell in love with the beautiful young Peg Amy from Sun Top Mountain; when she persisted in refusing him, Glegg transformed her into a tree. He pursued a complicated strategy over the space of three years to win her, only to be thwarted in the end by Prince Pompadore and Kabumpo the Elegant Elephant. (Kabumpo in Oz)
Glegg was punished by Ozma: he was forced to drink one of his own malicious potions, which caused him to explode into nothingness. [See: Death in Oz.]
The power and versatility of the sorcerer's magic is demonstrated in his creation of Glegg's Box of Mixed Magic.
Background
Author Ruth Plumly Thompson never describes Glegg, other than to call him a "dreadful old man." Artist John R. Neill pictures him as an aged grotesque, with an ugly face, few teeth, wild hair, a pot belly, and gangling limbs.
He was a tough and strong old fellow; Ozma destroyed him by having him force-fed a cup of his Triple Trick Tea - but it took fourteen of her people to do it.