2000
#5,944
National surname rank
Recorded bearers 5,331
First available Census row
Per 100,000 1.98
Rare Last name
Castor
An English occupational surname for a maker or seller of oil, ointment, or perfume.
According to the 2020 US Census Bureau surname tables, roughly 6,676 Americans carry the last name Castor. That puts it at #5,732 in the national surname ranking, appearing at a frequency of 1.95 per 100,000 people (about 1 in 51,341 residents).
This page is the full Name Census profile for the Castor 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
6.7K
1 in 51,341
Census rank
#5,732
2020 decennial data
Per 100,000
1.9
Frequency rate
Recorded bearers
5.8K
rare in the US
Popularity narrative
The Census Bureau recorded 5,822 bearers of the surname Castor in its 2020 decennial surname file. At a rate of 1.95 per 100,000 residents, it holds the 5732nd position in the national surname ranking.
Among Census respondents with the surname Castor, the largest self-reported group is White at 56.6%. The next largest groups are Hispanic (23.5%) and Black (11.8%).
Origin
Meaning and origin of Castor
The surname Castor is of French origin, with its roots tracing back to the Middle Ages. It is derived from the Old French word "castor," which means "beaver." The name likely originated as a descriptive nickname for someone who worked with beaver pelts or lived near a beaver dam.
The earliest recorded instances of the Castor surname can be found in French medieval records from the 13th and 14th centuries. One notable example is Jehan Castor, a merchant from Rouen mentioned in a document dated 1287. The name also appears in various forms, such as Lecastor and Lecasto, in records from Normandy and Picardy during this period.
In England, the Castor surname is believed to have been introduced by French Huguenot immigrants fleeing religious persecution in the 16th and 17th centuries. The name can be found in parish records from this time, particularly in areas with significant Huguenot settlements, such as London and Canterbury.
The Domesday Book, the comprehensive survey of England commissioned by William the Conqueror in 1086, does not contain any direct references to the Castor surname. However, it does mention several place names that may have influenced the name's development, such as Cossington (from the Old English "castor-tun," meaning "beaver town") and Castletown (from the Old English "castel-tun," meaning "castle town").
Notable individuals with the Castor surname throughout history include:
1. Jacques Castor (1563-1641), a French Protestant theologian and author from Normandy.
2. Marie Castor (1678-1742), a French courtier and mistress of King Louis XV.
3. John Castor (1775-1848), an English businessman and philanthropist from Yorkshire.
4. Henri Castor (1818-1892), a French painter and illustrator known for his depictions of rural life.
5. Marie-Thérèse Castor (1902-1981), a French author and journalist who wrote extensively about the French Resistance during World War II.
While the Castor surname has its origins in France, it has since spread to various parts of the world, including England, Canada, and the United States, through immigration and migration patterns over the centuries.
Demographics
Ancestry and ethnicity for Castor
Among Census respondents with the surname Castor, the largest self-reported group is White at 56.6%. The next largest groups are Hispanic (23.5%) and Black (11.8%).
The bar chart below shows how Castor 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 Castor surname at the time of the 2020 Census, not any inherent property of the name itself.
- White56.6% · 3,293
- Hispanic or Latino23.5% · 1,368
- Black or African American11.8% · 686
- Asian and Pacific Islander5.0% · 291
- Two or more races2.9% · 166
- American Indian and Alaska Native0.3% · 18
Timeline
Historical Census data for Castor
Castor 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
#5,722
National surname rank
Recorded bearers 6,063
+732 bearers (+13.7%)
Per 100,000 2.06
Rank movement Up 222 places
2020
#5,732
National surname rank
Recorded bearers 5,822
-241 bearers (-4.0%)
Per 100,000 1.95
Rank movement Down 10 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #5,944 | 5,331 | 1.98 | First available Census row | First available Census row |
| 2010 | #5,722 | 6,063 | 2.06 | +732 bearers (+13.7%) | Up 222 places |
| 2020 | #5,732 | 5,822 | 1.95 | -241 bearers (-4.0%) | Down 10 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 Castor 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 | #5,722 | #5,732 | -0.2% |
| Count | 6,063 | 5,822 | -4.0% |
| Per 100K | 2.06 | 1.95 | -5.4% |
Between the 2010 and 2020 Census, the number of Castor bearers went from 6,063 to 5,822 (-4.0% change). The surname moved down 10 positions in the national ranking, going from #5,722 to #5,732.
Notable bearers
Famous people with the surname Castor
FAQ
Castor surname: questions and answers
How many people in the U.S. have the surname Castor?
Name Census estimates that about 6,676 living Americans carry the surname Castor. Using the current population baseline, that works out to roughly 1 in 51,341 residents.
How common is Castor?
Castor ranks #5,732 in the 2020 Census surname tables and is classified on this site as "Rare." The Census recorded the name at a frequency of 1.95 per 100,000 residents, which is about 2 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 5,822 people with the surname Castor. That is different from the site's living-bearer estimate (6,676), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 1.95 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 1.95 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 2 of them to have the surname Castor.
Has Castor become more or less common over time?
Between 2010 and 2020, the surname Castor went from 6,063 recorded bearers to 5,822. That is a decrease of 241 (-4.0%). In the national ranking it fell from #5,722 to #5,732.
What does the Census say about the background of Castor?
Among Census respondents with the surname Castor, the largest self-reported group is White at 56.6%. The next largest groups are Hispanic (23.5%) and Black (11.8%). 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?
White is the largest self-reported group for the surname Castor in the 2020 Census, accounting for 56.6% (3,293 people in the source table).
What is the full ancestry breakdown?
Castor appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (56.6%), Hispanic (23.5%), Black (11.8%). 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 Castor (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 Castor mean?
An English occupational surname for a maker or seller of oil, ointment, or perfume. 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 Castor (1.95 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 Americans have the surname Castor?
For a quick modern estimate, our sister site HowManyOfMe.org answers that in one glance, with the living-bearer count front and centre.