Last name Castlo (Castlo 
) , all around the world, is a rare cognomen. The last name Castlo is characteristic of Egypt, where it is a rare surname, the United Kingdom, where it is a very rare surname, and Argentina, where it is an extremely rare surname. Measured by absolute frequency, it is the most numerous in Egypt, the United Kingdom, and the United States. Very seldom, Castlo is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Castlo | Mexico, Argentina, United Kingdom, United States, Egypt |