Castor is a distinctive boys' name in United States, ranking #7596 in 2011 with 10 recorded births. This places Castor in the bottom 47% 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 2011, approximately 1 in every 189,899 boys born was named Castor. RISING Recent data shows the name is currently rising.