Castor
An uncommon surname that can come from the Roman name Castor, or less often from a place-name such as Castor in Norfolk.
The #5,722 most common surname in the United States (2010 Census) — about 1 in every 50,923 Americans shares it.
Etymology
Castor is best understood as a surname taken from a personal name. The classical name Castor comes from Greek Kastōr, familiar from the twin hero Castor of Castor and Pollux in ancient mythology. In England, the surname may also sometimes be locational, referring to someone from a place called Castor, such as the village in Norfolk. Because the historical evidence is thin, different lines of origin may apply to different families.
History
The surname appears only lightly in the historical record, but the place-name Castor in Norfolk is attested in medieval documents and may have helped generate local bynames. Some 19th-century surname writers also treated Castor as a name influenced by classical and biblical-style naming fashions. In modern English-speaking countries it remains relatively rare.
Origin
Regions
Variant spellings
Fun fact
19th-century surname collectors noticed Castor as one of several unusual names that could sound either classical or locational, which is exactly the kind of ambiguity that makes it hard to pin down with certainty.
From the historical record
“Kizbr's Quest, p. iii. Robert Arthur, rector of Castor, co. Norf., 1334 : FF. ▼. 418. 1615. Robert Arthur and Margaret”
— A Dictionary of English and Welsh Surnames (alternate scan)