| Alberto Rey de Castro y Romaña | |
| Office: | Prime Minister of Peru |
| President: | Oscar R. Benavides |
| Term Start: | 18 May 1934 |
| Term End: | 25 December 1934 |
| Predecessor: | José de la Riva-Agüero y Osma |
| Successor: | Carlos Arenas y Loayza |
| Office2: | Minister of Justice |
| President2: | Oscar R. Benavides |
| Term Start2: | 18 May 1934 |
| Term End2: | 25 December 1934 |
| Predecessor2: | José de la Riva-Agüero y Osma |
| Successor2: | Carlos Arenas y Loayza |
| Office3: | Minister of Foreign Affairs |
| President3: | Oscar R. Benavides |
| Term Start3: | 5 September 1934 |
| Term End3: | 18 September 1934 |
| Predecessor3: | Solón Polo |
| Successor3: | Carlos Concha Cárdenas |
| Birth Date: | 1 July 1869 |
| Birth Place: | Arequipa, Peru |
| Death Place: | Arequipa, Peru |
| Spouse: | María López de Romaña y López de Romaña |
| Profession: | diplomat |
Alberto Rey de Castro y Romaña (1 July 1869 - 18 May 1961) was a Peruvian politician and diplomat. He was Prime Minister of Peru, Minister of Justice and Minister of Foreign Relations in 1934.
Rey de Castro was born in Arequipa, Peru. His parents were Ezequiel Rey de Castro y Maria Manuela de Romaña y Bustamante. He received his early education in Lima at Colegio de la Inmaculada and Liceo Carolino and obtained his PhD from the University of San Agustin de Arequipa.
He joined the diplomatic service, serving as Secretary at Peru's legation in England (1902) and Chile (1905-1908), Chargé d'affairs in Argentina (1911-1914) and Plenipotentiary Minister in Ecuador (1916-1919). He was also appointed to Bolivia in 1920, but did not serve.