Castor was a merchantman launched in 1782 that played a significant role in the maritime trade during the late 18th century.

The ship was associated with the British East India Company (EIC) and underwent several ownership changes before being last listed in 1808.

Lloyd's Register On 10 September 1793, Captain Joseph Salkeld, received a letter of marque for Castor.

Homeward bound, she was at Diamond Harbour on 7 June, and reached St Helena on 3 September.

That same source states that in 1802 Curling and Co., of London, purchased Castor for use as a West Indiaman.