Find out how popular the last name Guillermo is in the United States and learn more about the meaning, history, and race and ethnic origin of people in America who are named Guillermo.

Guillermo, like all of the last names we have data for, is identified by the U.S. Census Bureau as a surname which has more than 100 occurrences in the United States in the Decennial Census survey. The most recent statistics we have for the Guillermo surname is from the 2010 census data.

Popularity of Guillermo in America

Guillermo is the 9581st most popular name in America based on the data we have collected from the U.S. Census Bureau.

The Guillermo surname appeared 3,393 times in the 2010 census and if you were to sample 100,000 people in the United States, approximately 1 people would have the surname Guillermo.

We can also compare 2010 data for Guillermo to data from the previous census in 2000. The table below contains all of the statistics for both years in a side-by-side comparison.

The history of the last name 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.

Race and ethnic origin of people with the last name Guillermo

We also have some data on the ancestry of people with the surname Guillermo.

The below race categories are the modified race categories used in the Census Bureau's population estimates program. All people were categorized into six mutually exclusive racial and Hispanic origin groups:

1. White only
2. Black only
3. American Indian and Alaskan Native only
4. Asian and Pacific Islander only
5. Hispanic
6. Two or More Races

For the most recent 2010 census data, the race/ethnic origin breakdown for Guillermo was:

Note: Any fields showing (S) means the data was suppressed for privacy so that the data does not in any way identify any specific individuals.

Since we have data from the previous census in 2000, we can also compare the values to see how the popularity of Guillermo has changed in the 10 years between the two census surveys.

Data source

The last name data and ethnic breakdown of last names is sourced directly from the Decennial Census survey, conducted every 10 years by the United States Census Bureau.

The history and meaning of the name Guillermo was researched and written by our team of onomatology and genealogy experts.

If you have a correction or suggestion to improve the history of Guillermo, please contact us.

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