Castor Oyl is a character created by E.C. Segar for his comic strip Thimble Theatre, now known simply as Popeye. Castor is the quick-witted yet diminutive adventuring older brother of Olive Oyl, and both are the children of Cole Oyl and his wife Nana. Castor was originally an opportunistic adventurer who always tried to make money in any way he could, but, as time went by, he ended up finding his true calling as a detective, eventually becoming the head of his own agency.