Marianne Deborah Williamson is an American author, speaker, and politician. She began her professional career as spiritual leader of the Church of Today, a Unity Church in Warren, Michigan. Williamson has written several self-help books, including A Return to Love: Reflections on the Principles of A Course in Miracles in 1992, which became a New York Times Best Seller. She was launched into prominence by Oprah Winfrey, being a frequent guest on her daytime talk show and becoming known as her "spiritual advisor".

The 2020 presidential campaign of Marianne Williamson, an author, was announced on January 28, 2019, after the initial formation of an exploratory committee on November 15, 2018. Williamson's bid for the Democratic nomination was her second political campaign, after previously running as an independent to represent California's 33rd congressional district in 2014. Prior to her candidacy, Williamson was known as "Oprah's spiritual adviser" due to her frequent appearances on The Oprah Winfrey Show.