Castor
- Gender
- Boy
- Say it
- KAS-ter
- Origin
- Greek
- US rank, 2025
- #4,706 for boys
Castor is a boys' name of Greek origin, meaning “beaver”. In 2025 it ranked 4,706th for boys in the US (21 babies).
What does Castor mean?
Greek: from Greek Kastor
“beaver”
In Greek myth, Castor and his twin Pollux are the Dioscuri, remembered in the two brightest stars of Gemini.
Is Castor a girl's or a boy's name?
Castor is a boys' name. In 2025, it was given to 21 boys in the US. Too few girls were given it to be listed.
How popular is Castor in the US?
- Rank in 2025
- 4,706th among boys
- Babies in 2025
- 21 about 1 in 81,000 boys
- Five-year trend
- Falling down 37% in five years
- Same name in a class
- under 1% chance among 15 boys
In 2025, 21 boys in the US were named Castor, making it the 4,706th most popular name for boys. Five years earlier, in 2020, it was 3,915th. Its busiest year was 2016, with 29 boys. It first appears in the records in 1998.
2025 had more boys named Castor than any year since 2020.
Half of all the boys named Castor in the US since 1880 were born between 2009 and 2020, the years shaded on the chart below.
Castor in the US, year by year
| Year | Boys | Rank |
|---|---|---|
| 2025 | 21 | #4,706 |
| 2024 | 14 | #6,194 |
| 2023 | 11 | #7,284 |
| 2022 | 17 | #5,441 |
| 2021 | 17 | #5,333 |
| 2020 | 26 | #3,915 |
| 2019 | 23 | #4,333 |
| 2018 | 24 | #4,222 |
| 2017 | 14 | #6,056 |
| 2016 | 29 | #3,680 |
| 2015 | 17 | #5,285 |
| 2014 | 18 | #5,062 |
| 2013 | 17 | #5,167 |
| 2012 | 15 | #5,714 |
| 2011 | 10 | #7,495 |
| 2010 | 9 | #8,133 |
| 2009 | 13 | #6,432 |
| 2008 | 8 | #9,013 |
| 2007 | 8 | #8,909 |
| 2006 | 11 | #6,899 |
| 2005 | 9 | #7,633 |
| 2004 | 6 | #9,941 |
| 2003 | 7 | #8,636 |
| 2002 | 8 | #7,636 |
| 2001 | 9 | #6,928 |
| 2000 | 10 | #6,309 |
| 1999 | 8 | #7,132 |
| 1998 | 11 | #5,460 |
Nicknames for Castor
- Cass 29 boys in the UK in 2025
Names like Castor
Names given in the same years and the same naming tradition, with a similar sound.
Xander, Baylor, Ander, Cooper, Luca, Atlas, Archer, Colson, Ares, Theo, Callum, Wilder
More Greek names
Theodore, Sophia, George, Lucas, Sofia, Alexander, Sebastian, Penelope, Phoebe, Margot, Luke, Chloe, Sophie, Zoe, Iris, Maisie
Sources
Figures from Popular Baby Names (US Social Security Administration). Nameling last updated them on 20 October 2026. How the figures are worked out, and the data to download.
To cite this page: Nameling, “Castor: name meaning, origin and popularity”, https://www.nameling.co.uk/names/castor, updated 20 October 2026.