2000
#4,643
National surname rank
Recorded bearers 6,986
First available Census row
Per 100,000 2.59
Rare Last name
Molloy
An Irish surname derived from the Gaelic "Ó Maolmhuaidh," meaning "descendant of the devotee of Saint Mhuadh."
According to the 2020 US Census Bureau surname tables, roughly 8,018 Americans carry the last name Molloy. That puts it at #4,891 in the national surname ranking, appearing at a frequency of 2.34 per 100,000 people (about 1 in 42,748 residents).
This page is the full Name Census profile for the Molloy 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 Molloy with 1881 census detail, origin facts and modern UK distribution where available.
Bearers in the US
8.0K
1 in 42,748
Census rank
#4,891
2020 decennial data
Per 100,000
2.3
Frequency rate
Recorded bearers
7.0K
rare in the US
Popularity narrative
The Census Bureau recorded 6,992 bearers of the surname Molloy in its 2020 decennial surname file. At a rate of 2.34 per 100,000 residents, it holds the 4891st position in the national surname ranking.
Among Census respondents with the surname Molloy, the largest self-reported group is White at 90.9%. The next largest groups are Hispanic (4.5%) and Two or More Races (2.9%).
Origin
Meaning and origin of Molloy
The surname Molloy originated in Ireland, likely emerging sometime in the Middle Ages. It is an Anglicized form of the Gaelic name "O'Maolmhuaidh," which means "descendant of a devotee of St. Maolmhuaidh." The prefix "O'" indicates a male descendant, while "Maolmhuaidh" refers to a saint who lived during the 6th century.
The Molloy clan was historically based in County Offaly, a region in central Ireland. Some of the earliest recorded instances of the name can be found in medieval Irish annals and records, such as the Annals of the Four Masters, which mention several prominent members of the Molloy family during the 14th and 15th centuries.
One of the earliest known individuals with the Molloy surname was Tadhg O'Maolmhuaidh, a renowned Irish poet and scholar who lived in the late 14th century. He was a member of the esteemed bardic family of Clann O'Maolmhuaidh, who were renowned for their literary contributions.
Another notable figure was Terence Molloy, a Franciscan friar who lived in the 17th century. He was a prominent theologian and philosopher, and his works were widely circulated throughout Europe during the Renaissance period.
In the 18th century, Charles Molloy, an Irish lawyer and judge, gained recognition for his legal writings and contributions to the development of Irish law. His treatise "De Jure Maritimo et Navali" (On Maritime and Naval Law) was highly regarded in its time.
During the 19th century, Joseph Molloy, an Irish-born artist and illustrator, made a significant impact in the world of art. He was known for his detailed depictions of rural life in Ireland and contributed illustrations to several notable publications.
Another notable individual was William Molloy, an Irish-born American politician who served as the 37th Governor of Connecticut from 1907 to 1909. He was a prominent figure in the Democratic Party and played a role in shaping the state's political landscape during his tenure.
While the surname Molloy has its roots in Ireland, it has since spread to other parts of the world, particularly due to Irish emigration. However, its origins can be traced back to the ancient Gaelic name O'Maolmhuaidh and the historical clan that bore this name in County Offaly.
Demographics
Ancestry and ethnicity for Molloy
Among Census respondents with the surname Molloy, the largest self-reported group is White at 90.9%. The next largest groups are Hispanic (4.5%) and Two or More Races (2.9%).
The bar chart below shows how Molloy 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 Molloy surname at the time of the 2020 Census, not any inherent property of the name itself.
- White90.9% · 6,359
- Hispanic or Latino4.5% · 312
- Two or more races2.9% · 202
- Asian and Pacific Islander0.8% · 53
- Black or African American0.7% · 51
- American Indian and Alaska Native0.2% · 15
Timeline
Historical Census data for Molloy
Molloy 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
#4,868
National surname rank
Recorded bearers 7,238
+252 bearers (+3.6%)
Per 100,000 2.45
Rank movement Down 225 places
2020
#4,891
National surname rank
Recorded bearers 6,992
-246 bearers (-3.4%)
Per 100,000 2.34
Rank movement Down 23 places
| Year | Rank | Count | Per 100K | Count change | Rank change |
|---|---|---|---|---|---|
| 2000 | #4,643 | 6,986 | 2.59 | First available Census row | First available Census row |
| 2010 | #4,868 | 7,238 | 2.45 | +252 bearers (+3.6%) | Down 225 places |
| 2020 | #4,891 | 6,992 | 2.34 | -246 bearers (-3.4%) | Down 23 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 Molloy 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 | #4,868 | #4,891 | -0.5% |
| Count | 7,238 | 6,992 | -3.4% |
| Per 100K | 2.45 | 2.34 | -4.5% |
Between the 2010 and 2020 Census, the number of Molloy bearers went from 7,238 to 6,992 (-3.4% change). The surname moved down 23 positions in the national ranking, going from #4,868 to #4,891.
Notable bearers
Famous people with the surname Molloy
FAQ
Molloy surname: questions and answers
How many people in the U.S. have the surname Molloy?
Name Census estimates that about 8,018 living Americans carry the surname Molloy. Using the current population baseline, that works out to roughly 1 in 42,748 residents.
How common is Molloy?
Molloy ranks #4,891 in the 2020 Census surname tables and is classified on this site as "Rare." The Census recorded the name at a frequency of 2.34 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 6,992 people with the surname Molloy. That is different from the site's living-bearer estimate (8,018), which projects the surname's present-day count by applying the Census frequency rate to the current U.S. population.
What does 2.34 per 100,000 actually mean?
It is the Census Bureau's normalized frequency measure. A rate of 2.34 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 Molloy.
Has Molloy become more or less common over time?
Between 2010 and 2020, the surname Molloy went from 7,238 recorded bearers to 6,992. That is a decrease of 246 (-3.4%). In the national ranking it fell from #4,868 to #4,891.
What does the Census say about the background of Molloy?
Among Census respondents with the surname Molloy, the largest self-reported group is White at 90.9%. The next largest groups are Hispanic (4.5%) and Two or More Races (2.9%). 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 Molloy in the 2020 Census, accounting for 90.9% (6,359 people in the source table).
What is the full ancestry breakdown?
Molloy appears across multiple self-reported groups in the Census data. The largest shares in the 2020 file are White (90.9%), Hispanic (4.5%), Two or More Races (2.9%). 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 Molloy (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 Molloy mean?
An Irish surname derived from the Gaelic "Ó Maolmhuaidh," meaning "descendant of the devotee of Saint Mhuadh." 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 Molloy (2.34 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 have the surname Molloy?
HowManyOfMe.org, our sister site, answers that with the living-bearer count in one glance.