António de Saldanha da Gama, Count of Porto Santo (Lisbon, 5 February 1778 [1] – 1839) was a Portuguese politician, navy officer, diplomat and colonial administrator. [1] He was the Portuguese plenipotentiary at the Congress of Vienna in 1815. [2] [3] While at the Congress he signed a number of treaties and documents on behalf of Prince Regent John of Portugal including the Declaration of the Powers, on the Abolition of the Slave Trade, on 8 February 1815. [3] He was governor of the Portuguese colony Maranhão (northern Brazil) between 1804 and 1806, [4] and of Portuguese Angola between 1807 and 1810. [5] He was created count of Porto Santo on 26 October 1823. [1]