Around the world, William Arnoldo (William Arnoldo 
) is a very rare male first name. The first name William Arnoldo is characteristic of Latin America and the Caribbean, particularly Costa Rica, where it is a rare male name, and Chile, where it is a very rare boy's name. Much less frequently, William Arnoldo is the last name as well as the forename.
| VARIANT | COUNTRY |
|---|---|
| William Arnoldo | Costa Rica, Chile, Ecuador |