Sebastián de Covarrubias Horozco (Toledo, 1539–1613) was a Spanish writer, lexicographer, and priest. In his clerical capacity, he served as choir director and schoolmaster at the cathedral of Cuenca, consultant to the Inquisition, and chaplain to King Phillip II. In 1605 he began writing Tesoro de la lengua castellana o española (Treasure of the Castilian or Spanish Language), which, published in 1611, was among the first monolingual dictionaries of a European vernacular. Covarrubias is also the author of Emblemas morales (Moral Emblems), published in 1610; Tratado de cifras (Treatise on Ciphers) and a translation of Horace, now lost; and a Suplemento (Supplement), first published in 2001, that sought to add to the Treasure and amend its faults.