The name Guillermo is a boy's name of Spanish origin. Guillermo is ranked #793 on our popularity charts and is often added to lists like International Variations of William and discussed in our forums with posts like "Names on NB that make you go WOW!".
From the experts:
As with Guillaume (see above), Liam, Willem, and Wilhelm, everyday Williams in their own countries, Guillermo is a captivating possibility here. Giermo, Gigermo, Gijermo, Gillermo, Gillirmo, Giyermo, Guermillo, Guiermo Guilermón, Guille, Guillelmo, Guillermino, Guillo, Guirmo, Gullermo, Llermo, Memo, Quillermo.