Caim is a Gaelic rendering of biblical ' Cain', who appears in a variation of the fantastical pedigree of Dardanus of Troy that is spun out in Lebor Bretnach, the Middle Irish language recension of the compilation called Historia Brittonum, known in the 9th century version by Nennius. The Lebor Bretnach, greatly modifies the genealogy given in Nennius, making emendations to earlier sources and tracing the line through Ham rather than Japheth with further spurious names:Dardain m. Ioib m. Sadoirn m. Peil m. Palloir m. Zorastres m. Mesraim m. Caim.
In the predominantly Welsh-speaking regions of Wales (Gwynedd, Dyfed and Ynys Mon), Cain, Caio, Caim and Cail are commonplace first names for males. These names are derivatives of an ancient Welsh name "Ca" which is recorded in the book of Welsh folklore called the Mabinogion.
Caim is an outcast Duke of Hell, one of the Rabble of Devilkin, in the Dungeons & Dragons roleplaying game.