The Castilian War, or Spanish Expedition to Borneo, was a 1578 conflict between the Spanish Empire and the Bruneian Empire.

Castilian War may also refer to: Castilian war of succession (1282–1304) between Sancho IV of Castile and the Infantes de la Cerda Castilian Civil War of 1351–1369 between Peter of Castile and Henry II of Castile War of the Two Peters (1356–1375) between Peter of Castile and Peter IV of Aragon War of the Castilian Succession (1475–1479) between Isabella I of Castile and Joanna la Beltraneja Revolt of the Comuneros, or Castilian War of the Communities (1520–1) between Castilian Comuneros rebels and Castilian Royalists

See also Castilian Civil War