Oreilly
A surname of Irish origin, derived from the Gaelic "Ó Raghallaigh," meaning "descendant of Raghallach" (a personal name meaning "valiant").
According to the 2010 US Census Bureau surname tables, roughly 14,019 Americans carry the last name Oreilly. That puts it at #2,970 in the national surname ranking, appearing at a frequency of 4.09 per 100,000 people (about 1 in 24,449 residents).
This page is the full Name Census profile for the Oreilly surname. You will find the Census Bureau frequency data, 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
14K
1 in 24,449
Census rank
#2,970
2010 decennial data
Per 100,000
4.1
Frequency rate
Recorded bearers
12K
uncommon in the US
Popularity narrative
The Census Bureau recorded 12,074 bearers of the surname Oreilly in its 2010 decennial surname file. At a rate of 4.09 per 100,000 residents, it holds the 2970th position in the national surname ranking.
Among Census respondents with the surname Oreilly, the largest self-reported group is White at 91.9%. The next largest groups are Hispanic (3.5%) and Black (2.0%).
Origin
Meaning and origin of Oreilly
The surname O'Reilly is of Irish origin and dates back to the 11th century. It is derived from the Gaelic name Ó Raghallaigh, which means "descendant of Raghallach". The name Raghallach is a combination of the words "ragh", meaning "fortune", and "allach", meaning "prosperous" or "wealthy".
The O'Reillys were one of the most prominent and influential families in the ancient kingdom of East Bréifne, which covered parts of modern-day counties Cavan and Leitrim. They were lords of East Bréifne from the 11th century until the 17th century, and their stronghold was at Cavan town.
One of the earliest recorded mentions of the name can be found in the Annals of the Four Masters, a chronicle of medieval Irish history compiled in the 17th century. The annals document the exploits of various O'Reilly chieftains and their role in the political and military affairs of the region.
The name O'Reilly first appears in English records in the 13th century, with various spellings such as O'Reily, O'Reiley, and O'Rely. The Domesday Book, a historical record commissioned by William the Conqueror in 1086, does not include any references to the name, as it was a survey of landholders in England and parts of Wales.
Notable figures with the surname O'Reilly throughout history include:
1. Sir John O'Reilly (c. 1497 - 1562), an Irish chieftain and Lord of East Bréifne who played a significant role in the political and military struggles of 16th century Ireland.
2. Andrew O'Reilly (1742 - 1832), an Irish-born Spanish general who served in the Spanish Army during the American Revolutionary War and the Peninsular War against Napoleonic France.
3. Jeremiah O'Reilly (1831 - 1896), an Irish-American Catholic priest and president of the University of Notre Dame from 1864 to 1866.
4. John Boyle O'Reilly (1844 - 1890), an Irish-born American poet, novelist, and journalist who was a leading voice for Irish independence in the United States.
5. Mary O'Reilly (1888 - 1963), an Irish revolutionary and member of the Irish Republican Army who played a significant role in the Irish War of Independence and the Irish Civil War.
Demographics
Ancestry and ethnicity for Oreilly
Among Census respondents with the surname Oreilly, the largest self-reported group is White at 91.9%. The next largest groups are Hispanic (3.5%) and Black (2.0%).
The bar chart below shows how Oreilly bearers described their own race and ethnicity on the 2010 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.
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 Oreilly surname at the time of the 2010 Census, not any inherent property of the name itself.
- White91.9%
- Hispanic or Latino3.5%
- Black or African American2.0%
- Two or more races1.5%
- Asian and Pacific Islander0.7%
- American Indian and Alaska Native0.3%
Year on year
2010 vs 2010 Census
How has the Oreilly surname changed between Census years? The chart shows bearer count side by side, and the table compares rank, count, and frequency.
Census year comparison
| Metric | 2010 | 2010 | Change |
|---|---|---|---|
| Rank | #2,970 | #2,970 | 0.0% |
| Count | 12,074 | 12,074 | 0.0% |
| Per 100K | 4.09 | 4.09 | 0.0% |
Between the 2010 and 2010 Census, the number of Oreilly bearers went from 12,074 to 12,074 (+0.0% change). The surname held its position in the national ranking, going from #2,970 to #2,970.
Notable bearers
Famous people with the surname Oreilly
FAQ
Oreilly surname: questions and answers
How common is the last name Oreilly?
The surname Oreilly holds position #2,970 in the US Census Bureau's surname ranking, with an estimated 14,019 living bearers. It occurs at a rate of 4.09 per 100,000 Americans.
What is the ethnic background of the Oreilly surname?
Among Census respondents with the surname Oreilly, the largest self-reported group is White at 91.9%. The next largest groups are Hispanic (3.5%) and Black (2.0%). These figures come from the 2010 Census Bureau surname tables, based on how respondents described their own race and ethnicity.
Where does this surname data come from?
All surname statistics on Name Census are drawn from the US Census Bureau's decennial surname frequency tables. These tables list every surname that appeared 100 or more times in the 2010 Census, along with a frequency rate and self-reported demographic breakdown. You can read the full explanation on our methodology page.