2000
#11,647
National surname rank
Recorded bearers 2,469
First available Census row
Per 100,000 0.92
Rare Last name
Guillermo
A Spanish surname derived from the Germanic elements "wil" meaning "desire" and "helm" meaning "helmet" or "protection."
According to the 2020 US Census Bureau surname tables, roughly 4,104 Americans carry the last name Guillermo. That puts it at #8,791 in the national surname ranking, appearing at a frequency of 1.20 per 100,000 people (about 1 in 83,517 residents).
This page is the full Name Census profile for the Guillermo surname. You will find the Census Bureau frequency data, a multi-census history view, an ancestry and ethnicity breakdown based on self-reported demographics, the name's meaning and origin where available, and answers to the most common questions people ask about this surname.
Bearers in the US
4.1K
1 in 83,517
Census rank
#8,791
2020 decennial data
Per 100,000
1.2
Frequency rate
Recorded bearers
3.6K
rare in the US
Popularity narrative
The Census Bureau recorded 3,579 bearers of the surname Guillermo in its 2020 decennial surname file. At a rate of 1.20 per 100,000 residents, it holds the 8791st position in the national surname ranking.
Among Census respondents with the surname Guillermo, the largest self-reported group is Hispanic at 53.7%. The next largest groups are Asian/Pacific Islander (37.4%) and White (4.3%).
Origin
Meaning and origin of Guillermo
The surname Guillermo originated in Spain, with roots dating back to the Middle Ages. It is derived from the Germanic name Wilhelm, which means "resolute protector" or "willing helm" (helmet). The name was brought to Spain by the Visigoths, a Germanic tribe that ruled parts of the Iberian Peninsula in the 5th to 8th centuries.
During the Reconquista, the period when Christian kingdoms gradually regained control of the Iberian Peninsula from the Moors, the name Guillermo became widespread among the nobility and the upper classes. It was often Hispanicized to Guillermo or Gilberto.
One of the earliest recorded instances of the surname Guillermo can be found in the "Libro de las Estampas" (Book of Stamps), a 12th-century manuscript from the Kingdom of León. It mentions a nobleman named Guillermo de Toro, who held lands in the region of Tierra de Campos.
In the 13th century, a renowned knight named Guillermo de Montcada fought in the conquest of Valencia and was granted lands in the newly acquired territories. His descendants adopted Montcada as their surname, but the name Guillermo remained associated with the family for generations.
During the 14th century, a Castilian nobleman named Guillermo de Rocafull was recorded in the chronicles of the reign of Alfonso XI. He played a significant role in the Reconquista and was granted lands in Andalusia.
In the 15th century, a powerful family from Catalonia, the Guillermos de Requesens, held significant influence and wealth. One of its members, Guillermo de Requesens y Roís de Liori (1508-1537), was a renowned military commander who served under Emperor Charles V.
In the 16th century, a renowned Spanish explorer and conquistador, Guillermo de Riquelme (c. 1500-1548), was part of the expeditions that explored and conquered portions of present-day Mexico and Guatemala.
Over the centuries, the surname Guillermo has been associated with various noble families, military leaders, and prominent figures in Spanish history. While it originated as a personal name, it eventually became a well-established surname, particularly in regions like Catalonia, Andalusia, and Valencia.
Demographics
Ancestry and ethnicity for Guillermo
Among Census respondents with the surname Guillermo, the largest self-reported group is Hispanic at 53.7%. The next largest groups are Asian/Pacific Islander (37.4%) and White (4.3%).
The bar chart below shows how Guillermo bearers described their own race and ethnicity on the 2020 Census form. The Census Bureau groups responses into six broad categories: White, Black or African American, Hispanic or Latino, Asian and Pacific Islander, American Indian and Alaska Native, and Two or More Races. When a category has too few respondents for a given surname, the Bureau suppresses the figure to protect individual privacy, which is why some names show fewer than six slices.
Percentages are shown for every Census year so the breakdown stays comparable over time. When the source file also includes raw headcounts, Name Census shows those alongside the percentages in the legend.
Keep in mind that these are self-reported numbers. A person's surname does not determine their race or ethnicity, and the distribution you see here reflects the specific population who happened to carry the Guillermo surname at the time of the 2020 Census, not any inherent property of the name itself.
- Hispanic or Latino53.7% · 1,922
- Asian and Pacific Islander37.4% · 1,339
- White4.3% · 153
- Two or more races3.7% · 133
- Black or African American0.8% · 29
- American Indian and Alaska Native0.1% · 3
Timeline
Historical Census data for Guillermo
Guillermo appears in 3 published Census surname files: 2000, 2010, 2020. The cards below show how the name's rank and bearer count changed across each release.
2010
#9,581
National surname rank
Recorded bearers 3,393
+924 bearers (+37.4%)
Per 100,000 1.15
Rank movement Up 2,066 places
2020
#8,791
National surname rank
Recorded bearers 3,579
+186 bearers (+5.5%)
Per 100,000 1.20
Rank movement Up 790 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #11,647 | 2,469 | 0.92 | First available Census row | First available Census row |
| 2010 | #9,581 | 3,393 | 1.15 | +924 bearers (+37.4%) | Up 2,066 places |
| 2020 | #8,791 | 3,579 | 1.20 | +186 bearers (+5.5%) | Up 790 places |
For 2020, the Census Bureau published race and Hispanic-origin columns as counts rather than percentages. Name Census converts those counts back into shares so the ancestry section stays comparable with the older surname files.
Year on year
2010 vs 2020 Census
How has the Guillermo surname changed between Census years? The chart shows bearer count side by side, and the table compares rank, count, and frequency.
Census year comparison
20102020
| Metric | 2010 | 2020 | Change |
|---|---|---|---|
| Rank | #9,581 | #8,791 | 8.2% |
| Count | 3,393 | 3,579 | 5.5% |
| Per 100K | 1.15 | 1.20 | 4.1% |
Between the 2010 and 2020 Census, the number of Guillermo bearers went from 3,393 to 3,579 (+5.5% change). The surname moved up 790 positions in the national ranking, going from #9,581 to #8,791.
FAQ
Guillermo surname: questions and answers
How many people in the U.S. have the surname Guillermo?
Name Census estimates that about 4,104 living Americans carry the surname Guillermo. Using the current population baseline, that works out to roughly 1 in 83,517 residents.
How common is Guillermo?
Guillermo ranks #8,791 in the 2020 Census surname tables and is classified on this site as "Rare." The Census recorded the name at a frequency of 1.20 per 100,000 residents, which is about 1 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 3,579 people with the surname Guillermo. That is different from the site's living-bearer estimate (4,104), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 1.2 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 1.20 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 1 of them to have the surname Guillermo.
Has Guillermo become more or less common over time?
Between 2010 and 2020, the surname Guillermo went from 3,393 recorded bearers to 3,579. That is an increase of 186 (+5.5%). In the national ranking it rose from #9,581 to #8,791.
What does the Census say about the background of Guillermo?
Among Census respondents with the surname Guillermo, the largest self-reported group is Hispanic at 53.7%. The next largest groups are Asian/Pacific Islander (37.4%) and White (4.3%). These figures come from the 2020 Census Bureau surname tables, based on how respondents described their own race and ethnicity.
Which group reports this surname most often?
Hispanic is the largest self-reported group for the surname Guillermo in the 2020 Census, accounting for 53.7% (1,922 people in the source table).
What is the full ancestry breakdown?
Guillermo appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are Hispanic (53.7%), Asian/Pacific Islander (37.4%), White (4.3%). For 2020, the source file also published raw headcounts for each group, which is why this page can show both percentages and counts in the ancestry section.
Is this page using the latest Census data?
Yes. This page is using the latest surname file currently loaded on Name Census, which is 2020. The historical section above also keeps any older Census surname entries we have for Guillermo (2000, 2010, 2020).
Does the Census include every surname?
No. The Census Bureau only publishes surnames that appeared at least 100 times in a given decennial Census. That means very rare surnames are excluded entirely, and a surname can appear in one Census release but disappear from a later one if it falls below the reporting threshold.
Why don't the ancestry percentages always add up to exactly 100%?
There are two main reasons: rounding and suppression. The Census Bureau rounds published values, and it may suppress very small cells to protect privacy. For 2020, the Bureau also published raw group counts rather than direct percentages, so Name Census converts those counts back into shares for comparability across census years.
What does Guillermo mean?
A Spanish surname derived from the Germanic elements "wil" meaning "desire" and "helm" meaning "helmet" or "protection." The fuller origin note on this page goes into more detail.
Where does the surname data come from?
All surname statistics on Name Census are drawn from the US Census Bureau's decennial surname frequency tables. These files list every surname that appeared 100 or more times in the 2020 Census, along with a count, a per-100,000 rate, and a self-reported demographic breakdown. You can read the full explanation on our methodology page.
How does Name Census estimate living bearers?
For surnames, Name Census does not age cohorts the way it does for first names. Instead, it takes the Census Bureau's published frequency for Guillermo (1.20 per 100,000) and applies that rate to the current U.S. resident population to estimate how many living Americans have the surname today.
How many people have the surname Guillermo?
HowManyOfMe.org, our sister site, answers that with the living-bearer count in one glance.