Oneill
A Gaelic given name meaning "descendant of Niall" or "champion".
Name Census estimates that about 63 living Americans carry the first name Oneill. The name is used almost exclusively for boys. The average person named Oneill today is around 31 years old, and the year with the single highest number of Oneill births was 2010 (8 babies).
This page is the full Name Census profile for Oneill. Below you will find a gender breakdown showing how the name splits between male and female registrations, a year-by-year popularity chart stretching back to 1880, decade-level totals, the top US states for this name, its meaning and etymology, and a set of frequently asked questions with data-backed answers.
For a British comparison, Name Census UK has a UK baby-name profile for Oneill with official rankings and popularity over time.
Key insights
- • Fewer than 100 living Americans are believed to carry the name Oneill. It is among the rarest names in the SSA records.
People living today
63
~ 1 in 5,440,545 Americans
Peak year
2010
8 babies that year
Average age
31
years old
2017 SSA rank
#13,722
Tracked since 1918
Census
Oneill in the 2020 Census
The 2020 Census recorded 249 people with the first name Oneill, which placed it at #33,298 in the published first-name tables. This is a snapshot of people who already had the name at the time of the Census.
The SSA sections elsewhere on this page answer a different question: how often parents gave the name to babies over time. The "people living today" figure on this page is different again: it is a current estimate built from SSA birth records and age-based survival rates, so the two numbers are not expected to match exactly.
2020 Census rank
#33,298
National first-name rank
People counted
249
249 in the published race/origin table
Per 100,000
0.1
People with this name in 2020
Largest reported group
White
37.3% of people with this name
Demographics
Ancestry and ethnicity for Oneill
In the 2020 Census race and Hispanic-origin table, the largest reported group for people named Oneill is White at 37.3%. The next largest groups are Hispanic (28.9%) and Black (23.3%). These figures describe the people who had the name in 2020, not any inherent property of the name itself.
The bar chart below shows how people with the first name Oneill 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 name, the Bureau suppresses the figure to protect individual privacy, which is why some names show fewer than six slices.
Percentages are shown so the breakdown is easy to read across every published category. Because the 2020 Census first-name file also includes raw headcounts for each group, Name Census can show those alongside the percentages in the legend and hover tooltip.
Keep in mind that these are self-reported numbers. A first name does not determine a person's race or ethnicity, and the distribution you see here reflects the specific population who happened to carry the name Oneill at the time of the 2020 Census, not any inherent property of the name itself.
- White37.3% · 93
- Hispanic or Latino28.9% · 72
- Black or African American23.3% · 58
- Asian and Pacific Islander5.6% · 14
- Two or more races4.4% · 11
- American Indian and Alaska Native0.4% · 1
Popularity
Oneill: popularity over time
The SSA tracks Oneill from the 1910s through to the 2010s, spanning 8 decades of birth certificate data. The biggest single decade for the name was the 1980s, with 26 total registrations. The name continues to be given at rates close to its all-time high, suggesting it has not yet fallen out of fashion.
Babies born per year
Decades
Oneill by decade
The table below breaks the full SSA timeline into ten-year windows. Each row shows how many male and female babies were given the name Oneill during that decade, along with a combined total. This is useful for spotting eras where the name surged or retreated.
Origin
Meaning and history of Oneill
The given name Oneill has its origins in the Irish Gaelic language and culture. It is derived from the Old Irish words "Ua Néill" or "Ui Neill," which translate to "descendant of Niall" or "grandson of Niall." This name can be traced back to the semi-legendary High King of Ireland, Niall Noígiallach, who ruled in the late 4th and early 5th centuries AD.
The name Niall itself is believed to have been derived from the Old Irish word "niadh," meaning "champion" or "warrior." As such, the name Oneill has connotations of strength, bravery, and nobility associated with its origins.
The first recorded instances of the name Oneill can be found in ancient Irish genealogical records and annals, which document the lineage of the Uí Néill dynasties that dominated much of Ireland from the 5th to the 12th centuries. These dynasties, which included the Northern and Southern Uí Néill branches, were among the most powerful and influential ruling families in medieval Irish history.
Throughout history, several notable individuals have borne the first name Oneill. One of the earliest recorded examples is Oneill Ceanfhota, who was the King of Cenél nEógain (a branch of the Northern Uí Néill) in the late 6th century AD. Another prominent figure was Oneill Frossach, who ruled as the King of Ailech (the capital of the Northern Uí Néill) in the late 8th century.
In more recent times, Oneill Browne (1888-1923) was an Irish revolutionary and member of the Irish Republican Army during the Irish War of Independence. Additionally, Oneill Cronin (1928-2011) was an acclaimed Irish actor known for his performances in films such as "The Seventh Seal" and "Becket."
Other notable individuals with the first name Oneill include Oneill Latimer (1933-1992), an American lawyer and politician who served as the Governor of West Virginia, and Oneill Sanford (1963-present), an American singer and songwriter best known for his work with the band Hootie & the Blowfish.
People
Oneill + last name combinations
How many people share a full name with Oneill as the first name? Click a combination below to see the estimate, or search any pairing.
Related
Other names starting with O
Other first names starting with O with a similar number of bearers.
FAQ
Oneill: questions and answers
How many people in the U.S. are named Oneill?
Name Census puts the figure at roughly 63 living Americans. We arrive at this by taking every SSA birth registration for Oneill going back to 1880 and adjusting each cohort for expected survival using CDC actuarial life tables. The result is an age-weighted living-bearer count, not a raw birth total. That works out to about 1 in 5,440,545 US residents.
Is Oneill a common name?
We classify Oneill as "Very Rare". It ranks above 57.8% of all first names in the SSA dataset by living bearers. Across the full history of the data, 87 babies have been registered with this name.
When was Oneill most popular?
The single biggest year for Oneill was 2010, when 8 babies received the name. The fact that the average living Oneill is about 31 years old gives you a rough sense of which era contributed the most bearers who are still alive today.
How common was Oneill in the 2020 Census?
The published 2020 Census first-name tables recorded 249 people with the name Oneill, or 0.08 per 100,000 residents. That placed it at #33,298 in the national Census ranking for first names.
Why is the Census count different from the living estimate?
Because they measure different things. The Census figure is a count of people who had the name Oneill in 2020. The living estimate aims to answer a current question instead: how many people with the name are alive today, based on SSA birth records and age-based survival rates. Since one number is a 2020 snapshot and the other is a present-day estimate, they are not expected to be identical.
What does the Census say about the gender split for Oneill?
In the 2020 Census sex table, Oneill leans strongly male. 225 people counted with this name were male (89.6%), compared with 26 female bearers (10.4%). The Census view is a snapshot of people living with the name in 2020, while the SSA section above tracks births across time.
What does the Census say about the background of people named Oneill?
In the 2020 Census race and Hispanic-origin table, the largest reported group for people named Oneill is White at 37.3%. The next largest groups are Hispanic (28.9%) and Black (23.3%). These figures describe the people who had the name in 2020, not any inherent property of the name itself. The percentages in the chart above come from self-reported race and Hispanic-origin responses in the 2020 Census.
Which group reports the name Oneill most often in the Census?
White is the largest reported group for people named Oneill in the 2020 Census, accounting for 37.3% (93 people in the published table).
Why can the Census sex total and race total differ slightly?
The Census Bureau published separate 2020 tables for sex and for race/Hispanic origin, and the released figures can differ slightly because of privacy protection in the public files. That is why this page treats the gender section and the race/origin section as two related snapshots instead of forcing them into one identical total.
Does every first name have Census demographic data?
No. The public Census first-name release only includes names that met the Bureau's publication rules, so many rarer names in the SSA files have no Census demographic snapshot. When that happens, the SSA trend, gender history, and state sections still appear, but the 2020 Census demographic sections are omitted.
What does the SSA popularity chart show?
The chart tracks births, not the number of people alive with the name today. Each point shows how many babies were given the name Oneill in that year. That makes it useful for spotting when the name rose, peaked, or faded.
Is Oneill a male name?
Yes, 100.0% of people registered as Oneill in the SSA data are male. You can see the full per-sex comparison in the gender distribution section above, which includes the latest year rank, birth count, and peak year for each sex.
Is Oneill still being used today?
Yes. The SSA still recorded Oneill in 2024, and the page above shows its latest-year rank where available. A name can be well past its peak and still remain in steady use, especially if it built up a large population over earlier decades.
Why can a name have a lot of living bearers even if it is not trendy now?
Because living-bearer counts and current baby-name popularity measure different things. A name like Oneill can build up a very large population over many decades, even if fewer parents are choosing it now than they did at its peak.
Where does this data come from?
First-name figures come from the Social Security Administration's national baby name files, which cover every name on a birth certificate from 1880 to 2024. Living-bearer estimates layer in CDC actuarial life tables broken out by sex to account for mortality. The population baseline (342,754,338) is the Census Bureau's latest national estimate. You can read the full calculation on our methodology page.
How many people have Oneill as a first name?
If you just want to know how many people have the name Oneill, HowManyOfMe.org gives you the headline number in one glance.