El Castillo (in Spanish: Castle) is a census-designated place located in Starr County, Texas, United States. It is a new CDP, formed from part of the old La Victoria CDP for the 2010 census. As of the 2020 census, El Castillo had a population of 219.
El Castillo is located at (26.334926, -98.638659). According to the United States Census Bureau, El Castillo has a total area of 0.07 km<sup>2</sup>, all land.
El Castillo along with 5 other census designated places (Alto Bonito Heights, El Socio, Eugenio Saenz, Olmito and Olmito, and Valle Vista) was formed prior to the 2010 U.S. census from parts of La Victoria CDP.
According to the 2010 US Census, there were 188 people residing in El Castillo. The density was 2,686 inhabitants/km<sup>2</sup>. Populated for 188 inhabitants, El Castillo was composed of the 76.06% white, the 22.87% of other races and the 1.06% belonged to two or more races. Of the total population, 100% were Hispanic and Latino of any race.
The CDP is within the Rio Grande City Grulla Independent School District (formerly Rio Grande City Consolidated Independent School District)