Castor is a distinctive boys' name in United States, ranking #4734 in 2025 with 21 recorded births. This places Castor in the top 34% of ranked US boys' names for the year. Its actual usage is classified as Rare. The name reached its all-time peak in 2016 with 29 births ranking #3702. In 2025, approximately 1 in every 81,337 boys born was named Castor. RISING Recent data shows the name is currently rising.