El Castillo (in Spanish: Castle) is a census-designated place located in Starr County, Texas, United States.

[3] According to the United States Census Bureau, El Castillo has a total area of 0.07 km2, all land.

[4] 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.

[17] According to the 2010 US Census, there were 188 people residing in El Castillo.

[21] The CDP is within the Rio Grande City Grulla Independent School District (formerly Rio Grande City Consolidated Independent School District)[22]