Mrs. Who is one of the characters of the A Wrinkle In Time novel.
In the book, she is described as a plump woman who wears glasses. She communicates in Latin, Spanish, Italian, German, French, Portuguese and Greek, notably quoting William Shakespeare, Pascal, Dante, Seneca, A. Perez, Horace, Cervantes, Delille, Euripides, the Bible and Goethe. Mrs. Whatsit explains that Mrs. Who finds it "difficult to verbalize" in her own words.
As seen in the 2018 show:
She shows great talent in memorizing details in books which she describes as "human books". After talking too much, she shows great energy used, as seen in the movie. After talking to Meg, Charles Wallace, and Calvin, she passed out and slept.