Manuel Fernández de Santa Cruz y Sahagún (18 January 1637, Palencia (Spain) – 1 February 1699, Puebla (Mexico)) was a religious writer and Roman Catholic prelate who served as Bishop of Guadalajara (19 February 1674–2 June 1676), and Bishop of Tlaxcala (2 June 1676–1 February 1699).
As well as founding charitable institutions in his diocese, he published Sor Juana's Carta atenagórica (critiquing a sermon by António Vieira) - without her permission (albeit under a pseudonym) and told her to focus on religious instead of secular studies, despite agreeing with her criticisms.