the wizard
In author Gregory Maguire's
Wicked: The Life and Times of the Wicked Witch of the West (a 1995 revisionist novel based on the inhabitants of Oz) and in the 2003 Broadway musical
Wicked (based on Maguire's novel), the Wizard is a tyrannical ruler who uses deceit and trickery to hide his own shortcomings. Unlike in earlier works, the Wizard is clearly meant to be the villain of the story.
Maguire presents the Wizard as a con man and a hustler who happened onto a world where he could literally make himself into a king overnight. Pretending to have vast powers and all-encompassing knowledge, he rules over the Emerald City, while secretly requiring people with true magic talent such as Glinda and Elphaba to cast spells for him.
During the course of Maguire's novel and the subsequent Broadway production, it is revealed that the Wizard is indeed behind some of the most horrific and disastrous events in the story, with one of his cohorts being Madame Morrible. The Wizard is revealed as the illegitimate father of Elphaba, seducing her mother with a magical green elixir, causing Elphaba's green tone. In the musical, this fact is revealed to the character Glinda, who accosts the Wizard with this information. It is also under the Wizard's direction that the Animals of Oz - most notably the Goat teacher from Shiz University, Doctor Dillamond - are caged and placed under strict control. This cruelty causes the final split between Elphaba and the Wizard, leading to her transformation into the Wicked Witch of the West.
No more than a con man with knowledge of how to work with human emotion and beliefs, this version of the Wizard works to maintain his own position and prestige, regardless of the pain and grief it causes to others, and is not beyond subversion or mandated murder.
The Wizard is portrayed in a slightly better light in the musical, Wicked. Instead of being very amoral, he is carried away by the belief of the people of Oz that he is "wonderful." When he learns that Elphaba is his daughter, he expresses visible sorrow when he learns of her (supposed) death, agreeing with Glinda to leave Oz in his balloon.