* Mrs. Whatsit: A wise and eccentric woman who often appears in the form of a large, winged creature. She is a powerful being with a love of nature and a deep understanding of the universe.
* Mrs. Who: A quiet and scholarly woman who speaks in quotations. She is deeply knowledgeable about history and literature and often provides cryptic clues to help Meg and her friends.
* Mrs. Which: A stern and direct woman who is the most powerful of the three. She often appears as a shimmering, almost transparent figure.
While their exact nature is never fully explained in the book, they are described as "Celestial beings" who come from another dimension and are powerful enough to manipulate time and space.
It's important to note that L'Engle intentionally leaves their true nature somewhat ambiguous, allowing readers to interpret their identities and motivations. This adds to the mystical and allegorical nature of the story.