Originally an ordinary scarecrow crafted by a farmer near Munchkin Country to deter crows, Spaventapasseri gained sentience but remained immobilized on his pole, convinced he lacked intelligence. Dorothy Gale discovered him during her journey along the yellow brick road, releasing him and inspiring his quest to reach the Emerald City so the Wizard of Oz might grant him brains.

Throughout the trek, Spaventapasseri repeatedly overcame obstacles despite his perceived limitations. He engineered the Kalidahs’ defeat by felling the tree they crossed and coordinated the rescue of the Cowardly Lion from a lethal poppy field by collaborating with the Tin Woodman and the Queen of the Field Mice, exhibiting strategic ingenuity that his companions consistently noted.

When the Wizard demanded the Wicked Witch of the West’s elimination before granting requests, Spaventapasseri joined the mission. Winged Monkeys later scattered his stuffing in the Witch’s territory, though the Winkies restored him after Dorothy defeated the Witch. Exposed as a fraud, the Wizard provided Spaventapasseri a placebo—a head stuffed with bran, pins, and needles—symbolically fulfilling his wish and appointing him to rule the Emerald City.

His governance faced upheaval when General Jinjur’s Army of Revolt staged a coup, temporarily ousting him. After Princess Ozma’s ascension, he transitioned to an advisory role in her court, often favoring leisure over duty. Later residing in a corn-shaped house in Winkie Country, he undertook diplomatic missions like aiding Cap'n Bill, Trot, and Button-Bright to liberate Jinxland from King Krewl. Oz’s inhabitants, including the Tin Woodman who deemed him "probably the wisest man in all Oz," upheld his reputation for wisdom.

Spaventapasseri engaged in ongoing philosophical debates with the Tin Woodman about intellect versus emotion, reflecting his persistent self-image as a knowledge seeker. His adventures expanded beyond his origins, traversing diverse regions of Oz and neighboring lands.