Surname Sebastian Guillermo (Sebastian Guillermo 
) , across the world, is a rare cognomen. The last name Sebastian Guillermo is characteristic of Chile, where it is quite a rare surname, and Italy, where it is an extremely rare surname. More frequently, Sebastian Guillermo is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Sebastian Guillermo | Spain, Argentina, Peru, Ecuador, Chile |