2000
#3,242
National surname rank
Recorded bearers 10,121
First available Census row
Per 100,000 3.75
Uncommon Last name
Cosby
Derived from a place name meaning "Copp's farm" or "Cobb's farm" in Old English.
According to the 2020 US Census Bureau surname tables, roughly 11,595 Americans carry the last name Cosby. That puts it at #3,449 in the national surname ranking, appearing at a frequency of 3.38 per 100,000 people (about 1 in 29,561 residents).
This page is the full Name Census profile for the Cosby 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.
For British records, Name Census UK has a British surname profile for Cosby with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
12K
1 in 29,561
Census rank
#3,449
2020 decennial data
Per 100,000
3.4
Frequency rate
Recorded bearers
10K
uncommon in the US
Popularity narrative
The Census Bureau recorded 10,111 bearers of the surname Cosby in its 2020 decennial surname file. At a rate of 3.38 per 100,000 residents, it holds the 3449th position in the national surname ranking.
Among Census respondents with the surname Cosby, the largest self-reported group is White at 46.2%. The next largest groups are Black (43.2%) and Two or More Races (5.7%).
Origin
Meaning and origin of Cosby
The surname Cosby is believed to have originated in England, potentially derived from a place name or a descriptive term. One theory suggests that it may be rooted in the Old English words "cocc," meaning a worker or servant, and "by," meaning a town or village, indicating a possible connection to a settlement where servants or workers resided.
Another hypothesis links the name to the Old Norse word "kos," meaning a small hut or cottage, combined with the Old English "by," suggesting it could refer to a person who lived in a small dwelling or hamlet. However, the exact origins remain uncertain, as surnames often evolved and transformed over time.
In terms of historical references, the Cosby surname appears in various medieval records, such as the Hundred Rolls of Huntingdonshire from the 13th century, which mentions a William Cosebi. The Subsidy Rolls of Worcestershire from 1327 also list a John Coseby, indicating the name's presence in different regions of England.
One of the earliest recorded instances of the name is found in the Domesday Book of 1086, which documents a landowner named Robertus de Cozebi in Leicestershire. This entry suggests that the name may have been associated with a place called Cosby or a similar-sounding location.
Over the centuries, the surname has been spelled in various ways, including Coseby, Cozeby, Cosseby, and Cosbie, reflecting the fluidity of spelling conventions in earlier times. Some notable individuals bearing the Cosby surname include:
1. Sir Thomas Cosby (c. 1500-1572), an English soldier and landowner who served as Lord Lieutenant of Hertfordshire.
2. Philips Cosby (c. 1580-1625), an English colonist and landowner in Virginia, regarded as one of the earliest settlers in the Jamestown colony.
3. William Cosby (1690-1737), an English military officer and colonial governor of New York and New Jersey.
4. Grace Cosby (1892-1976), an American actress and vaudeville performer known for her roles in silent films.
5. William Henry Cosby Jr. (1937-present), an American stand-up comedian, actor, and author, widely known for his influential career in entertainment.
It is important to note that while the surname Cosby has been associated with various historical figures and locations, its precise origins remain subject to scholarly debate and ongoing research.
Demographics
Ancestry and ethnicity for Cosby
Among Census respondents with the surname Cosby, the largest self-reported group is White at 46.2%. The next largest groups are Black (43.2%) and Two or More Races (5.7%).
The bar chart below shows how Cosby 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 Cosby surname at the time of the 2020 Census, not any inherent property of the name itself.
- White46.2% · 4,670
- Black or African American43.2% · 4,371
- Two or more races5.7% · 578
- Hispanic or Latino3.8% · 385
- Asian and Pacific Islander0.5% · 54
- American Indian and Alaska Native0.5% · 53
Timeline
Historical Census data for Cosby
Cosby 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
#3,471
National surname rank
Recorded bearers 10,300
+179 bearers (+1.8%)
Per 100,000 3.49
Rank movement Down 229 places
2020
#3,449
National surname rank
Recorded bearers 10,111
-189 bearers (-1.8%)
Per 100,000 3.38
Rank movement Up 22 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #3,242 | 10,121 | 3.75 | First available Census row | First available Census row |
| 2010 | #3,471 | 10,300 | 3.49 | +179 bearers (+1.8%) | Down 229 places |
| 2020 | #3,449 | 10,111 | 3.38 | -189 bearers (-1.8%) | Up 22 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 Cosby 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 | #3,471 | #3,449 | 0.6% |
| Count | 10,300 | 10,111 | -1.8% |
| Per 100K | 3.49 | 3.38 | -3.1% |
Between the 2010 and 2020 Census, the number of Cosby bearers went from 10,300 to 10,111 (-1.8% change). The surname moved up 22 positions in the national ranking, going from #3,471 to #3,449.
Notable bearers
Famous people with the surname Cosby
FAQ
Cosby surname: questions and answers
How many people in the U.S. have the surname Cosby?
Name Census estimates that about 11,595 living Americans carry the surname Cosby. Using the current population baseline, that works out to roughly 1 in 29,561 residents.
How common is Cosby?
Cosby ranks #3,449 in the 2020 Census surname tables and is classified on this site as "Uncommon." The Census recorded the name at a frequency of 3.38 per 100,000 residents, which is about 3 people out of every 100,000.
How many people with this surname were counted in the Census?
The raw 2020 Census file counted 10,111 people with the surname Cosby. That is different from the site's living-bearer estimate (11,595), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 3.38 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 3.38 per 100,000 means that if you picked a random group of 100,000 U.S. residents, you would expect about 3 of them to have the surname Cosby.
Has Cosby become more or less common over time?
Between 2010 and 2020, the surname Cosby went from 10,300 recorded bearers to 10,111. That is a decrease of 189 (-1.8%). In the national ranking it rose from #3,471 to #3,449.
What does the Census say about the background of Cosby?
Among Census respondents with the surname Cosby, the largest self-reported group is White at 46.2%. The next largest groups are Black (43.2%) and Two or More Races (5.7%). 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 Cosby in the 2020 Census, accounting for 46.2% (4,670 people in the source table).
What is the full ancestry breakdown?
Cosby appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (46.2%), Black (43.2%), Two or More Races (5.7%). 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 Cosby (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 Cosby mean?
Derived from a place name meaning "Copp's farm" or "Cobb's farm" in Old English. 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 Cosby (3.38 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 Cosby?
HowManyOfMe.org, our sister site, answers that with the living-bearer count in one glance.