Barangay San Nicolas

Barangay San Nicolas is a mid-sized barangay in the municipality of Castillejos, located in the province of Zambales, in the Central Luzon region of the Philippines.

According to the 2020 Philippine census, Barangay San Nicolas had a population of 4,388. This made it the 6th largest of 14 barangays in Castillejos by population, placing it in the middle tier of the municipality. Residents of Barangay San Nicolas accounted for approximately 6.46% of the total population of Castillejos, which stood at 67,889 in the same census year.

Between the 2015 and 2020 censuses, the population of Barangay San Nicolas changed from 4,893 to 4,388, a shift of -10.3% over the five-year period. This places the barangay among those with contracting populations in Castillejos. Barangay San Nicolas is officially classified as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Castillejos is a municipality comprising 14 barangays, and serves as the governing unit directly responsible for local services in Barangay San Nicolas, including public health, sanitation, peace and order, and civil registration. Within the wider province of Zambales, which contains 247 barangays across its component cities and municipalities, Barangay San Nicolas ranks 35th by 2020 population. Zambales is classified as a 2nd by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

The barangay's legislative and executive affairs are handled by a Punong Barangay and the Sangguniang Barangay, elected nationwide during the Barangay and SK Elections. The next BSKE is scheduled for Monday, November 2, 2026, following the synchronized election schedule set by COMELEC Resolution No. 11191.