Mercedes Castro Díaz (Ferrol, La Coruña, Spain, 1972) is a Spanish writer.
Her first novel, Y punto, (2008, Alfaguara) was written over a period of nine years, and received some thirty rave reviews.  She believes that women are better able to create crime novels because they are more attentive to the details and psychological profiles of the characters. The author considers that this novel does not belong to the detective genre, and prefers that it be included within contemporary narrative, without ascription to a specific genre. This novel was distinguished as "Best First Opera in Spanish" by the Festival of First Novel of Chambéry (France).
His second novel, Mantis (2010, Alfaguara), published two years later, is a thriller that mixes psychological intrigue and gothic novel. It was included in the list of the 10 best novels of the year by the literary critic Ricardo Senabre for the supplement El Cultural of the newspaper El Mundo.
Among her signed literary editions are a critical edition of Benito Pérez Galdós' "Trafalgar" (2001), and "Antología poética de Rosalía de Castro" (2004), the first bilingual anthology of Rosalía de Castro published. Her first published work was the collection of poems La niña en rebajas (2001).
She lives in the city of Madrid.
La niña en rebajas (2001, Sociedad de Cultura Valle-Inclán de Ferrol), poetry book.