Jack's head is a carved pumpkin with a jolly expression. His tall figure is made from tree limbs and jointed with wooden pegs. He wears purple trousers, a red shirt, a pink vest with white polka dots, stockings, and shoes.Jack is not known for his intelligence which seems to depend on the quality and number of the seeds in his pumpkin-head at that time. However he does manage to come up with random bits of wisdom and common sense.
Jack was made by a little boy named Tip to scare his guardian, an old witch named Mombi. However, instead of being frightened, Mombi used Jack to test her new Powder of Life. The powder worked and Jack came to life. When Tip ran away from Mombi, he took Jack with him and headed south for the Emerald City. (The Marvelous Land of Oz)
Later, Jack settled in a house near the Tin Woodman's castle in Winkie Country. It made from a monstrous big pumpkin, hollowed out with a door and windows cut into the rind. A stovepipe runs through the stem, and six steps lead up to the front door.
Jack spends much of his time growing pumpkins to replace his old heads, which eventually spoil and need to be replaced. Apparently, Princess Ozma (whom he still calls "father") carves new heads for Jack when necessary. The old heads are buried in a graveyard on his property. (The Road to Oz) Jack also designed a five story, jewel-encrusted, corn-shaped mansion for the Scarecrow. (The Emerald City of Oz)
Jack is featured heavily in all 3 Lost in Oz novels and is one of Joshua Patrick Dudley's favorite Oz characters.
In the first Lost in Oz, Jack delivers the prophecy that changes Joshua's life.
In the two sequels, Jack has become friends with Joshua and is constantly trying to aid him on his journey and help him find success.
- The Marvelous Land of Oz (first appearance)
- The Road to Oz
- The Emerald City of Oz
- The Royal Book of Oz
- Jack Pumpkinhead of Oz
- Lost in Oz
- Lost in Oz: Rise of the Dark Wizard
- Lost in Oz: Temple of the Deadly Desert
In his Utopia Americana (1929), Edward Wagenknecht argued that L. Frank Baum's creation of Jack was influenced by Nathaniel's Hawthorne's short story "Feathertop."
Jack had to wait until the 23rd Oz book to get a book named after himself along with the starring role. Jack Pumpkinhead of Oz was written by Ruth Plumly Thompson, the writer who continued the Oz books after the death of L. Frank Baum.
Jack appears in the animated movie sequel Journey Back to Oz (which had a different outcome for the character), and the live-action movie Return to Oz.