Castor of Rhodes, Greek grammarian and rhetorician
Drusus the Younger, Roman consul, son of the Emperor Tiberius, nicknamed "Castor" Saint Castor of Apt, French bishop of Apt Saint Castor of Karden, German priest and hermit
Castor Cantero, Paraguayan football player
Castor McCord, American jazz saxophonist
Castor, French word for "beaver"
Castor Troy, villain in the movie 'Face/Off'
Castor Oyl, character in the Popeye cartoons
Castor, character in the video game "Spartan: Total Warrior" Lord Castor, character in the 2007 movie "The Harpy"
Castor, character in movie "Tron: Legacy,"
Castor, Gobernador, character in 'The Courts of the Morning" by John Buchan
Castor Wilds, location in video game "The Legend of Zelda: The Minish Cap"
Castor, character in the Hunger Games series
Castor, used on TV series Orphan Black (details=spoiler)