Lorenzo Annibale Costantino Nigra, Count of Villa Castelnuovo (11 June 1828 – 1 July 1907), was an Italian nobleman, philologist, poet, diplomat, and politician.

On the conclusion of peace, he entered the Kingdom of Piedmont-Sardinia's foreign office; he accompanied King Victor Emmanuel II and Camillo Benso, Count of Cavour, to Paris and London in 1855.

He was recalled from Paris when the occupation of the Marche and Umbria by the Piedmontese caused a breach in Franco–Italian relations, and was appointed secretary of state to the prince of Carignano, viceroy of the Neapolitan provinces.

[1] When Napoleon recognized the Kingdom of Italy in 1861, Nigra returned to France as minister-resident, and for many years played a most important part in political affairs and for Cavour; for his account of the administration of the Neapolitan provinces, Giustino Fortunato judged it an "admirable brave writing ... that is worth so much gold".

[1] He was a sound classical scholar, and published translations of many Greek and Latin poems with valuable comments; he was also a poet and the author of several works of folklore and popular poetry, of which the most important is his Canti popolari del Piemonte.