Meaning & origin
What it means
Castor goes back to Ancient Greek κάστωρ, meaning “beaver.”
Adapted from Wiktionary (CC BY-SA 4.0)
Where it comes from
An origin associated with this spelling is Greek.
How it developed
From Ancient Greek Κάστωρ, from Ancient Greek κάστωρ (“beaver”).
Adapted from Wiktionary (CC BY-SA 4.0)
The story
Published U.S. birth records include this spelling as early as 1998. This is the earliest published observation available here, rather than a date for the name’s origin.
From dated birth records
Castor through the years
- Babies since 1880
- 390
- 390 boys · 0 girls
- Most popular year
- 2016
- 29 babies
- 2025
- 21
- #4,734 for boys
- 2021–25 vs 2016–20
- −31%
- Easing
By the numbers
In 2025, this name appeared in 21 U.S. birth records for boys, ranking No. 4,734 among boys’ names. Average annual use for boys was 31.0% lower in 2021–2025 than in 2016–2020. Its largest published annual count for boys was 29 in 2016. Published U.S. population figures for this spelling include 454 as a first name in 2020; 5,822 as a surname in 2020.
From Social Security birth records and U.S. Census name counts for this exact spelling. Other spellings are counted separately.
Castor’s family of names
Castor has a related form in Castro. Castor has a related form in Caster. Castor has a related form in Castar.
Inner ring: nicknames and forms · outer: across languages.
Nicknames & forms 9
Diminutives, pet forms, short forms and variants used alongside the name.
- Castrovariant
- Castervariant
- Castorovariant
- Castoreovariant
- Castoriovariant
- Castyrvariant
- Castirvariant
- Castarvariant
Show 1 moreShow fewer
Across languages 3
Equivalents and cognates in other languages, plus older forms it grew from.
People named Castor
- Castor CanteroParaguayan footballerborn 1918
- Castor of Kardenpriest and hermit400–400
- Castor Paul MsemwaRoman Catholic bishop (1955–2017)
- Castor of Aptbishop of Apt350–420
- Castor ElzoSpanish footballer (1917-1989)
Listed by how widely each person is written about, which says nothing about the name itself.
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