2000
#8,195
National surname rank
Recorded bearers 3,726
First available Census row
Per 100,000 1.38
Rare Last name
Killen
Anglicized form of the Irish surname Ó Cillín, meaning "descendant of Cillín," a personal name of uncertain origin.
According to the 2020 US Census Bureau surname tables, roughly 4,002 Americans carry the last name Killen. That puts it at #8,995 in the national surname ranking, appearing at a frequency of 1.17 per 100,000 people (about 1 in 85,646 residents).
This page is the full Name Census profile for the Killen 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 Killen with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
4.0K
1 in 85,646
Census rank
#8,995
2020 decennial data
Per 100,000
1.2
Frequency rate
Recorded bearers
3.5K
rare in the US
Popularity narrative
The Census Bureau recorded 3,490 bearers of the surname Killen in its 2020 decennial surname file. At a rate of 1.17 per 100,000 residents, it holds the 8995th position in the national surname ranking.
Among Census respondents with the surname Killen, the largest self-reported group is White at 87.3%. The next largest groups are Black (4.7%) and Two or More Races (3.6%).
Origin
Meaning and origin of Killen
The surname Killen is believed to have originated in Ireland, deriving from the Gaelic personal name Cillian, which means "bright-headed" or "slender and fair." The name is thought to have first appeared in the 7th or 8th century AD, during the period of early Irish Christianity.
Killen is a variant spelling of the more common Irish surname Killeen, which is an anglicized form of the Gaelic name Ó Cillín. The prefix "Ó" signifies a descendant or grandson, indicating that the name refers to the descendants of a person named Cillian.
One of the earliest recorded instances of the name Killen can be found in the Annals of Ulster, a chronicle of medieval Irish history. The Annals mention a certain "Cillene" who was the abbot of Ardbraccan, County Meath, in the year 785 AD.
In the 11th century, the name appears in the form "Cillin" in the Book of Leinster, a medieval Irish manuscript containing genealogies and historical accounts. The Book of Leinster references a "Cillin mac Conmaic," who was a member of the Uí Dúnchada, a prominent family in the ancient kingdom of Leinster.
Notable individuals with the surname Killen throughout history include:
1. Sir Thomas Killen (1640-1706), an Irish judge and politician who served as Lord Chief Justice of Ireland.
2. William Killen (1806-1902), an Irish Presbyterian minister and author known for his work "The Ancient Church: Its History, Doctrine, Worship, and Constitution."
3. John Killen (1858-1927), an Irish-American politician who served as a member of the United States House of Representatives from Texas.
4. Brendan Killen (1836-1898), an Irish-born Australian Catholic priest and educator who founded several schools and colleges in Victoria.
5. William D. Killen (1917-2005), an American jurist who served as a judge on the United States District Court for the Northern District of Florida.
The surname Killen has also been associated with various place names in Ireland, such as Killenard (County Laois) and Killenkere (County Cavan), which may have influenced the spelling variations of the name over time.
Demographics
Ancestry and ethnicity for Killen
Among Census respondents with the surname Killen, the largest self-reported group is White at 87.3%. The next largest groups are Black (4.7%) and Two or More Races (3.6%).
The bar chart below shows how Killen 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 Killen surname at the time of the 2020 Census, not any inherent property of the name itself.
- White87.3% · 3,048
- Black or African American4.7% · 164
- Two or more races3.6% · 126
- Hispanic or Latino3.3% · 115
- Asian and Pacific Islander0.7% · 25
- American Indian and Alaska Native0.3% · 12
Timeline
Historical Census data for Killen
Killen 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
#7,968
National surname rank
Recorded bearers 4,151
+425 bearers (+11.4%)
Per 100,000 1.41
Rank movement Up 227 places
2020
#8,995
National surname rank
Recorded bearers 3,490
-661 bearers (-15.9%)
Per 100,000 1.17
Rank movement Down 1,027 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #8,195 | 3,726 | 1.38 | First available Census row | First available Census row |
| 2010 | #7,968 | 4,151 | 1.41 | +425 bearers (+11.4%) | Up 227 places |
| 2020 | #8,995 | 3,490 | 1.17 | -661 bearers (-15.9%) | Down 1,027 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 Killen 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 | #7,968 | #8,995 | -12.9% |
| Count | 4,151 | 3,490 | -15.9% |
| Per 100K | 1.41 | 1.17 | -17.2% |
Between the 2010 and 2020 Census, the number of Killen bearers went from 4,151 to 3,490 (-15.9% change). The surname moved down 1,027 positions in the national ranking, going from #7,968 to #8,995.
FAQ
Killen surname: questions and answers
How many people in the U.S. have the surname Killen?
Name Census estimates that about 4,002 living Americans carry the surname Killen. Using the current population baseline, that works out to roughly 1 in 85,646 residents.
How common is Killen?
Killen ranks #8,995 in the 2020 Census surname tables and is classified on this site as "Rare." The Census recorded the name at a frequency of 1.17 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 3,490 people with the surname Killen. That is different from the site's living-bearer estimate (4,002), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 1.17 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 1.17 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 Killen.
Has Killen become more or less common over time?
Between 2010 and 2020, the surname Killen went from 4,151 recorded bearers to 3,490. That is a decrease of 661 (-15.9%). In the national ranking it fell from #7,968 to #8,995.
What does the Census say about the background of Killen?
Among Census respondents with the surname Killen, the largest self-reported group is White at 87.3%. The next largest groups are Black (4.7%) and Two or More Races (3.6%). 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 Killen in the 2020 Census, accounting for 87.3% (3,048 people in the source table).
What is the full ancestry breakdown?
Killen appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (87.3%), Black (4.7%), Two or More Races (3.6%). 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 Killen (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 Killen mean?
Anglicized form of the Irish surname Ó Cillín, meaning "descendant of Cillín," a personal name of uncertain origin. 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 Killen (1.17 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 are called Killen?
Find out how many people have the last name Killen on our sister site HowManyOfMe.org — a quick modern estimate with the living-bearer count front and centre.