Around the globe, Guilliermo (Guilliermo 
) is a very rare primarily masculine, but very seldom female forename. The forename Guilliermo is characteristic of Israel, where it is a rare masculine name, and Philippines, where it is a very rare primarily male, but very infrequently feminine name. Very seldom, Guilliermo is the last name as well as the forename.
| VARIANT | COUNTRY |
|---|---|
| Guilliermo | Canada, Argentina, Philippines, United States, Israel |