Surname Fernández Castillo (Fernández Castillo 
) , in the world, is a very rare cognomen. The cognomen Fernández Castillo is habitual in Spain, where it is a very rare surname, Finland, and Peru. Measured by absolute frequency, the name is most common in Spain, Colombia, and Peru.
| VARIANT | COUNTRY |
|---|---|
| Fernández Castillo | Spain, Mexico, Finland, Colombia, Peru |