Guillermo Fernández-Shaw Iturralde (26 February 1893 - 17 August 1965) was a Spanish poet and journalist.
He is particularly known as a writer of libretti, primarily for zarzuelas.
With Federico Romero, he wrote the libretti for two of the best-known zarzuelas of the 20th century, Doña Francisquita by Amadeo Vives and Luisa Fernanda by Federico Moreno Torroba.
His father, Carlos Fernández Shaw, was also a playwright, poet and journalist who wrote libretti for several zarzuelas and operas, most famously Margarita la tornera and La vida breve.
Guillermo Fernández-Shaw was born in Cádiz and initially trained as a lawyer before becoming a journalist.
He was the editor of the Spanish newspaper La Epoca from 1911 to 1936, and a contributor to ABC as well as writing poetry for Blanco y Negro.
His partnership with Federico Romero began in 1916 with their libretto for Serrano's La canción del olvido.
Guillermo Fernández-Shaw died in Madrid on 17 August 1965 at the age of 72.