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- Richard D. James, electronica producer who works under pseudonyms such as Aphex Twin, and AFX amongst others
- Kenneth Hamilton Jenkin, Cornish historian, especially of Cornish tin mining
- Henry Jenner, scholar and leader of the revival of Cornish
- George Birch Jerrard, mathematician
- Thomas Brown Jordan, engineer
- Richard Jose, singer
- Dan Joyce, skateboarder and member of Dirty Sanchez
Read more about this topic: List Of People From Cornwall