How Many People Are Named Thaddeus Osullivan?
There are approximately 1 people named Thaddeus Osullivan living in the United States today. That makes this name combination very rare, occurring at a rate of about 1 in 342,754,338 Americans.
This estimate combines SSA birth records for the first name Thaddeus with Census Bureau frequency data for the surname Osullivan. Below you will find a breakdown of both names, including popularity trends, gender data, and ancestry information.
Estimated People with This Name
1
1 in 342,754,338 Americans
Combination Rarity
Very Rare
First Name
View full profileThaddeus
Last Name
View full profileOsullivan
Thaddeus: Popularity Over Time
Year-by-year SSA birth registrations for the first name Thaddeus. The peak year was 2016 with 416 births. The average person named Thaddeus today is 39 years old.
Ancestry of the Osullivan Surname
Self-reported race and ethnicity breakdown for people with the surname Osullivan, from the 2010 U.S. Census Bureau.
How we calculated this
The first name "Thaddeus" has an estimated frequency of < 0.0001% among living Americans, based on SSA birth records from 1880 to 2024 adjusted for mortality using CDC 2023 life tables.
The surname "Osullivan" appears at a rate of 4.01 per 100,000 people in the 2010 U.S. Census.
Multiplying these frequencies against the U.S. population of ~343 million gives 1 estimated people. This assumes first names and last names are statistically independent. Full methodology.
Other people named Thaddeus
Other people with the surname Osullivan
Thaddeus Osullivan: Questions and Answers
How many people are named Thaddeus Osullivan?
We estimate approximately 1 people named Thaddeus Osullivan are alive in the United States today. The first name Thaddeus is shared by 18,360 Americans, and the surname Osullivan is shared by 13,469.
How rare is the name Thaddeus Osullivan?
This name combination is classified as Very Rare, occurring at a rate of about 1 in 342,754,338 Americans. The first name Thaddeus is uncommon and the surname Osullivan is uncommon.
Is Thaddeus a male or female name?
Thaddeus is predominantly male, with 99.9% of bearers being male and 0.1% female. It peaked in popularity in 2016 and the average bearer today is 39 years old.
Where does this data come from?
First name data comes from the Social Security Administration (1880 to 2024), adjusted for survival using CDC 2023 life tables. Surname data comes from the 2010 U.S. Census Bureau. Full methodology.
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