Francisco Javier Saenz de Oiza (Caseda, 12 October 1918 - Madrid, 18 July 2000) was a Spanish architect and influential practitioner of the modernist movement in Spain. Oiza went to school in Seville and studied architecture in Madrid. After a study trip to the United States, in 1949 he returned to Madrid where he started teaching at the School of Architecture, later becoming its director.

One of his most noted works is the Torre Blancas a mixed-use building in Madrid with a cylindrical facade. With a height of 71 metres, it was built between 1964 and 1969. The facade consists of cylindrical volumes crowned by round overhanging balconies. Other notable projects include the Arantzazu Basilica in Onati, the Torre Triana administrative building in Seville, the Spanish embassy in Brussels, the Public University of Navarra in Pamplona, the remodelling of an old palace in Las Palmas, Gran Canaria, into the Atlantic Centre of Modern Art, and the Banco de Bilbao Tower in Madrid.