John Wilson (1741–1793) was an English mathematician who got a beautiful theorem named after him almost by accident — and then promptly gave up maths entirely to become a judge. He was a brilliant student at Cambridge, spotted a striking pattern about prime numbers as a young man, and then moved on to a comfortable career in law, leaving the hard part (the proof) to someone else.
The result now called
Here's the twist: Wilson never proved his own theorem, and he probably wasn't even the first to notice it — the pattern seems to have been known to the great medieval scholar Ibn al-Haytham centuries earlier. Wilson's teacher Edward Waring announced the result, Wilson got the credit, and it was left to Lagrange to actually prove it a few years later. So a theorem carries the name of a man who neither discovered it first nor proved it — a nice reminder that fame in mathematics can be delightfully unfair.