Uncle Henry is Dorothy Gale's uncle and husband to Aunt Em, living with them on a struggling farm in Kansas's gray prairies. Their sun-bleached one-room home reflects their hardship. Henry labors ceaselessly from dawn to dusk, managing the farm and livestock with Dorothy's help. Years of toil and financial strain render him stern and solemn, his gray hair and worn clothes mirroring the bleak landscape.

A cyclone transports their farmhouse to Oz, killing the Wicked Witch of the East. After returning to Kansas, Henry mortgages the farm to rebuild, worsening their debts. Dorothy’s disappearance during the event and sudden return exacerbates his declining health. Following medical advice, he takes Dorothy on a sea voyage to Australia, where she vanishes in a storm. Her magical return alleviates his despondency, but subsequent financial crises—including foreclosure threats from rebuilding and travel debts—force Henry and Em to reveal their desperation to Dorothy.

Dorothy orchestrates their permanent relocation to Oz’s Emerald City as Princess Ozma’s guests. Henry becomes Keeper of the Jewels in Ozma’s treasury, later evolving into Agricultural Adviser. He teaches advanced farming to Ozites, boosting crop yields and filling the Emerald City’s storehouses. His adaptability and expertise, contrasting with Em’s skepticism, earn him a trusted advisory role.

Adaptations diverge: one depicts him with a cyclone-induced broken leg, listless until Dorothy’s return revitalizes him; another reimagines him as a diner owner; an early film casts him as a villain. The television series "Lost" references Baum through a character alias "Henry Gale." Though later media established "Gale" as Dorothy’s surname, Baum’s original books omit this detail and leave Henry’s exact familial tie ambiguous.