Tommaso Costo was an Italian Renaissance humanist and writer.
Tommaso Costo was born in Naples around 1545. After completing his studies, he served as secretary for various noble families, including the Carafa and the Pignatelli. In 1586 Costo became secretary of the Neapolitan Accademia degli Svegliati. In 1591, he was admitted to the Accademia della Crusca. In 1599 he was appointed Secretary of the Grand Court of the Admiralty by the Prince of Conca, Matteo di Capua, Great Admiral of Naples. He drew on the experience he gained in these years for his Trattato dell'officio del segretario (1604). He died shortly after 1613.
Costo devoted himself to writing poems, short stories and historical works. He was acquainted with some important Neapolitan men of letters of the day, including the poet and scholar Giovanni Battista Attendolo, the poet and historian Angelo di Costanzo and the scholar Julius Capaccio. In his first work, the epic La rotta di Lepanto (1573), he celebrates the victory of the Holy League over the Ottoman Navy in the battle of Lepanto. His best known work is Il fuggilozio (1601), a collection of short stories modeled on Boccaccio's Decameron, dedicated to Matteo di Capua, and reissued several times. He also edited a valuable edition of Torquato Tasso's Jerusalem Delivered, published in Naples in 1582.