The Wicked Witch of the West is a fictional character and the main antagonist of the classic children's novel The Wonderful Wizard of Oz (1900), created by American author L. Frank Baum. In Baum's subsequent Oz novels, it is the Nome King who is the principal villain; the Wicked Witch of the West is rarely even referred to again after her death in the first book.

The witch's most popular depiction was in the classic 1939 film based on Baum's novel, where she was portrayed by Margaret Hamilton. Hamilton's characterization introduced green skin and this has been continued in later literary and dramatic representations, including Gregory Maguire's revisionist Oz novel Wicked: The Life and Times of the Wicked Witch of the West (1995) and its musical stage adaptation Wicked (2003), the 2013 film Oz the Great and Powerful, and the television series Once Upon a Time and Emerald City.