Helen Castor is a historian of medieval England and a Bye-Fellow of Sidney Sussex College, Cambridge. Her first book, Blood and Roses, was long-listed for the Samuel Johnson Prize in 2005 and won the English Association's Beatrice White Prize in 2006. Her second book, She-Wolves, was selected as one of the books of the year for 2010 by the Guardian, the Sunday Times, the Independent, Financial Times, and BBC History Magazine. She lives in London.