The Scarecrow is a fictional character in Gregory Maguire's reinvisonment novels. He is one of the traveling companions of Dorothy Gale, being discovered along her journey down the Yellow Brick Road. After the Wizard's departure, the Scarecrow would temporarily become a Throne Minister of Oz, before being deposed and replaced by Shell Thropp.
In the Novel
In Wicked: The Life and Times of the Wicked Witch of the West, Elphaba suspects that the Scarecrow was her lover Fiyero coming back to her in a disguise. Like in the original 1900 book by Baum and the 1939 movie by MGM, the Witch has her Flying Monkeys rip him to shreds and tear the straw out of the Scarecrow's clothing. In Wicked, Elphaba does this to make certain if he was Fiyero or not, but the Monkeys only find nothing but straw. Despite this, Elphaba believes it could have been the spirit of Fiyero within the straw itself. It is left to the reader of the book to choose if the Scarecrow was possessed by his spirit or not.
In Son of a Witch, it is the Scarecrow who talks to Elphaba's teenage son Liir after Dorothy Gale leaves Oz and is sent back home to Kansas. He warns him that Dirt Boulevard, the slum he is living in, is about to be 'cleaned up' by the authorities, and helps him escape from the purge. He brings Elphaba's broom to Liir, which Palace officials were going to throw out. Before he and Liir part ways, he tells Liir that he is not planning to remain in the Emerald City, explaining: "One day you're a celebrity, the next day you're hauled off to jail." The Scarecrow also tells Liir that he knew Dorothy was not from this world, did not belong in Oz, and had to leave.
Later on, after the Wizard leaves, the Scarecrow is made the Throne Minister, after the brief installment of Glinda Upland. However, Liir doesn't believe the Scarecrow who sat on the throne was the one who he spoke with prior, nor the one who befriended Dorothy. Liir thinks the Scarecrow on the throne was a mere 'performer', a human in a costume to fool the citizens of Oz, who are a gullible bunch and doubts if the Scarecrow is even still alive and stuffed together. Later, though "an unfortunate accident involving a beaker of lighter fluid", the Scarecrow is deposed and is replaced as Throne Minister by Shell Thropp, who would later crown himself Emperor Apostle of Oz.
In the Musical
In the musical, Wicked, Fiyero turns into the Scarecrow after Elphaba chants a spell to save his life during the song, No Good Deed. He can be seen for the first time during the Finale song when he opens a trap door to release Elphaba. The pair leave Oz to start a new life, as both of them are presumed dead.