Guillermo
Guillermo was the 902nd most popular name for boys in 2025, given to 264 babies. Its best year was 1996, when it ranked 352nd; the most babies were born in 1998 (693). Over the last ten years it has moved down 241 places. More babies were named Guillermo in the 1990s than in any other decade.
Meaning Spanish form of William · Spanish, Germanic
Say it gee-YAIR-moh /ɡiˈjɛɹmoʊ/
- Rank in 2025
- #902 boys, down 70 places since 2020
- Babies in 2025
- 264boys
- Girls and boys
- Almost always a boy’s name2021–2025
- Peak year
- 1998693 babies
- Total since 1880
- 32,148babies recorded
What does the name Guillermo mean?
Guillermo is the Spanish form of William, from the Germanic name Willahelm, made of wil 'will, desire' and helm 'helmet, protection'. The name came into Spanish through Old French Guillaume, the Norman form that also gave English William. Well-known bearers include the film director Guillermo del Toro.
wil (Old High German, “will, desire”)helm (Old High German, “helmet, protection”)
How sure is this? Well established.
Related names: William, Guillaume, Memo, Guillermina.
See also: Germanic names, names that mean protector.
Sources for this meaning
- Wiktionary, entry 'Guillermo' (Spanish section), Wiktionary (CC BY-SA 4.0; facts restated, no text reused)
- Wiktionary, entry 'William', Wiktionary (CC BY-SA 4.0; facts restated, no text reused)
- Dictionary of Medieval Names from European Sources, ed. S. L. Uckelman, Edition 2023 no. 1, s.v. 'William', DMNES (Durham University)
Nicknames for Guillermo
The usual nicknames for Guillermo are Memo and Willy. Some parents skip the long form: for every 100 boys named Guillermo in the last five years, 9 were named Willy, against 8 twenty years earlier.
| Nickname | Kind | Rank 2025 | Boys, 5 years |
|---|---|---|---|
| Memo · Mexican Spanish pet form | Traditional | — | — |
| Willy | Modern | #4,041 | 132 |
Nicknames reviewed by our editors; counts are boys given the nickname as their legal first name. Nobody records how many Guillermos go by each one.
Guillermo popularity since 1880
A few girls are given the name too: 74 since 1966.
| Year | Rank (boys) | Babies (boys) |
|---|---|---|
| 2025 | #902 | 264 |
| 2020 | #832 | 275 |
| 2010 | #553 | 457 |
| 2000 | #392 | 651 |
| 1990 | #395 | 587 |
| 1980 | #409 | 395 |
| 1970 | #472 | 290 |
| 1960 | #565 | 191 |
| 1950 | #608 | 127 |
| 1940 | #726 | 71 |
| 1930 | #611 | 101 |
| 1920 | #813 | 68 |
| 1910 | #895 | 13 |
| 1900 | #1,225 | 6 |
| 1890 | — | — |
| 1880 | — | — |
How popular is Guillermo, counting every spelling?
Guillermo has no other common spelling that sounds the same. Counting every name's spellings together, it ranks #867 for boys in 2025, against #902 on the official list.
How many kids will share the name Guillermo?
264 of the 3,606,400 babies born in the US in 2025 were named Guillermo (0.07 per 1,000 births). For a boy named Guillermo born in 2025, the chance that another child with the same name is in a class of 20 children the same age is under 1 in 50. If every grade liked the name as much as the 2025 babies do, only about one elementary school in 32 (of 430 pupils) would have a child named Guillermo.
Shares of all registered births (NCHS); classes assumed to be children born the same year. How we estimate this.
How old are people named Guillermo?
About 27,900 people born in the US named Guillermo are alive today, with a median age of 31; half are between 19 and 45. That makes Guillermo mostly worn by adults in their thirties to fifties.
Babies given the name each year (SSA) times the share of that birth year still alive (SSA life tables). Counts people born in the US only. Method.
Guillermo by state
How common Guillermo was among boys born in each state in 2021–2025. It is notably more common than nationally in Arizona (2.7×), Texas (2.6×), California (2.4×). In 31 states fewer than five boys a year got the name, too few for SSA to publish, so those states show as zero.
Names with a similar history
These names rose and fell in step with Guillermo: their share of US boys followed the most similar curve since 1880. If you like Guillermo, they share its era and feel.
Middle names for Guillermo · Sibling names for Guillermo
Questions about the name Guillermo
What does Guillermo mean?
Guillermo means “Spanish form of William” (Spanish, Germanic origin). Certainty: well established.
How popular is the name Guillermo?
Guillermo was the 902nd most popular name for boys in 2025, given to 264 babies. Its best year was 1996, when it ranked 352nd; the most babies were born in 1998 (693). Over the last ten years it has moved down 241 places. More babies were named Guillermo in the 1990s than in any other decade.
Is Guillermo a boy or girl name?
In 2021–2025, almost always a boy’s name given the name Guillermo in the US.
Where is Guillermo most popular?
In 2021–2025, Guillermo was most common in Arizona (0.45 per 1,000 boys), followed by Texas and California.