This post’s title is somewhat misleading. The duchess of Alba who died recently (see e.g. The Guardian‘s obituary) was herself the object of a lot of yellow press publishing but not a known publisher herself, as far as this blogger knows. But her third son, Jacobo Fitz-James Stuart, count of Siruela, aka Jacobo Siruela (Madrid, 1954; Spanish Wikipedia) is a writer, graphic designer, gardener and, foremost, has been a successful publisher with the Siruela (until 2005) and Atalanta (since 2005) publishing houses. Thus, he made a lot of 20th century thinkers and classics known to Spanish readers. More information in English on Atalanta‘s homepage.
This blogger became aware of the “importance” of Siruela because they were the first to publish Fred Vargas’ crime novels in Spanish.