Susannah Cahalan is an American writer and author. She works as a reporter at the New York Post and previously served as a news reporter and idea generator for the Sunday New York Post. She also works as a freelance books reviewer for the Postscript section.

Cahalan is known for writing the memoir "Brain on Fire: My Month of Madness," which details her hospitalization. The book was published in December 2012 by Simon & Schuster's imprint Free Press.