Luís Alves de Lima e Silva, Duke of Caxias (IPA: /kaˈʃiɐs/ or /kaˈʃiɐʃ/) (August 25, 1803 – May 7, 1880) was a Brazilian military leader and statesman. In more than one occasion, he served as Prime Minister of the Brazilian Empire. Considered one of the most important heroes in Brazilian military history, Caxias fought in the Argentina-Brazil War, the War of Tatters, Platine War, and, most notably, in the War of Triple Alliance. He was the only Brazilian not related to the House of Braganza to receive the honorary title of Duke (the others being Auguste de Beauharnais, Duke of Santa Cruz and the Duchesses of Goiás and Ceará, illegitimate daughters of Emperor Pedro I), and the only Duke to be created in the reign of Emperor Pedro II.

Caxias entered the military while in adolescence, and rapidly rose to the ranks of General and Baron, subsequently becoming Marshal, Count, Marquis, Senator, and Aide-de-Camp to the Emperor. He was twice Minister of War and also President of the Council, exerting great political influence as a conservative leader. Caxias was superseded as commander of the Brazilian Forces by the Count d'Eu after the capture of Asunción, and received the title of Duke in 1869. The Brazilian holiday Dia do Soldado (Portuguese, "Day of the Soldier"), celebrated on his birthday, August 25, and the cities of Duque de Caxias and Caxias do Sul are named in his honor. He is honoured as the Patron of the Brazilian Army.