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Guillermo

♂ Boy

Pronounced gee-YAIR-moh /ɡiˈjɛr.moʊ/High

Meaning: Spanish form of William, from Old High German Willahelm, composed of wil (will, desire, determination) and helm (helmet, protection); meaning resolute protector or one who wills to protectHigh

In 30 seconds: Guillermo is the Spanish form of William, from the Germanic Willahelm meaning resolute protector, a beloved classic across the Spanish-speaking world with notable bearers in art, film, and literature.
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Origin HighGermanic, Spanish
MeaningSpanish form of William, from Old High German Willahelm, composed of wil (will, desire, determination) and helm (helmet, protection); meaning resolute protector or one who wills to protect
U.S. rank (2025)#902 ↘ Falling
2025 U.S. births264 boys (0.01% of U.S. boys)
Peak year1998
Total births (all-time)≈ 32,071

Popularity in the U.S. · SSA data

peak 199818852025

U.S. births per year (Social Security Administration, 1880–present). Pink marker = peak year.

History & Origin

Guillermo is the Spanish adaptation of Germanic Willahelm, which reached Spain through Latin and Old French Guillaume after the medieval Frankish expansion. The Germanic components are wil (will, determination, desire) and helm (helmet, protection, shield), giving the full meaning of resolute protector or one with the will to protect. The name was brought to Spain during the Reconquista period and into Latin America through the Spanish colonial expansion from the 16th century onward.

Guillermo is a staple name across Spain, Mexico, Argentina, Colombia, and the broader Spanish-speaking world. In the United States it is used primarily by Hispanic communities. Notable bearers include Oscar-winning director Guillermo del Toro, known for Pan's Labyrinth and The Shape of Water, who has made the name internationally recognisable in contemporary cinema. The name also shares recognizability with its famous English cousin William and offers parents the option of the nickname Memo in Latin American usage.

Did you know? The name William — of which Guillermo is the Spanish form — has been the most common boys name in England for a remarkable stretch of history: it arrived with William the Conqueror in 1066 and remained dominant for centuries, reflecting how thoroughly a single conqueror's name can reshape a language's naming culture.
Overall data confidence 95%
Behind the Name — Guillermo — Spanish form and Germanic origin

Variations

GuillermeGuillemWilliam

Nicknames

MemoGuilleWilly

Famous Bearers

  • ★Guillermo del Toro (1964–present)
    Mexican film director and writer known for Pan's Labyrinth and The Shape of Water, for which he won Academy Awards for Best Director and Best Picture.

If you like Guillermo…

Fernando— three-syllable classic Spanish masculine name with the same dignified, Old World character
Alejandro— four-syllable Spanish classic with comparable historical depth and cultural weight
Roberto— three-syllable Spanish form of a Germanic name sharing Guillermo's Romance heritage
Antonio— three-syllable Spanish classic name with the same warm, cultivated Spanish character

Frequently Asked

What does Guillermo mean?

Guillermo is the Spanish form of William, from Old High German meaning resolute protector — combining will and helmet.

How do you pronounce Guillermo?

It is said gee-YAIR-moh — three syllables, stress on the second, with a silent u in gui-.

Is Guillermo the Spanish for William?

Yes, Guillermo is the Spanish equivalent of the English William and the French Guillaume.

What is a nickname for Guillermo?

Common nicknames include Memo (especially in Mexico) and Guille.