| Honorific-Prefix: | Count |
| Joaquim Pimenta de Castro | |
| Office2: | Prime Minister of Portugal |
| Term Start2: | 25 January 1915 |
| Term End2: | 14 May 1915 |
| President2: | Manuel de Arriaga |
| Predecessor2: | Vítor Hugo de Azevedo Coutinho |
| Successor2: | Constitutional Junta João Chagas (designate) |
| Birth Date: | 1846 11, df=yes |
| Birth Place: | Monção, Portugal |
| Death Place: | Lisbon, Portugal |
| Party: | Independent |
| Spouse: | Emília de Freitas |
| Alma Mater: | University of Coimbra |
| Occupation: | Army officer (General), and mathematician |
| Signature: | AssinaturaJoaquimPimentaDeCastro.svg |
Joaquim Pereira Pimenta de Castro (5 November 1846, in Pias, Monção – 14 May 1918, in Lisbon; pronounced as /pt/) was a Portuguese army officer and politician. He was a career military officer reaching the position of General, also graduated in mathematics by the University of Coimbra. In 1908, he was nominated commander of the 3rd Military Region, in Porto. After the proclamation of the Republic on 5 October 1910, he was Minister of War, for only two months, in 1911. He had to resign due to the monarchist incursion of Henrique de Paiva Couceiro. An independent, he was chosen by President Manuel de Arriaga to be the President of the Ministry (Prime Minister) of a government, who would rule without the parliament, where the Portuguese Republican Party, led by Afonso Costa had the majority. His government, with the support of the moderate Evolutionist Party and the Republican Union, and also conservative military factions, was in office from 28 January to 14 May 1915. It was overthrown by the military movement of 14 May 1915, supported by the Republican Party, which also caused the resignation of President Manuel de Arriaga.