### Clue: Aargh, typo's spoilt my theorem (10)
### Answer: PYTHAGORAS 
 ### Explanation: Definition: my theorem
  **Anagram of**(spoilt) AARGH, TYPO'S. 
Answer: Of Samos, to be more precise, the ancient Greek mathematician, philosopher and founder of a religious movement, after whom that famous theorem is named – there is some evidence that knowledge of it predates him.  Another trivia:  This theorem has more proofs than any other mathematical theorem.