Who is the inventor of irrational numbers?

Answer 1

An ancient Greek mathematician in the era of Pythagoras is said to have been murdered by his fellow secret society members for discovering the (now well-known) proof that square root of 2 is irrational.

Answer 2

It is believed that Irrational Numbers were known in ancient India but there was no formal proof of their existence as a separate class of numbers. The proof is sometimes attributed to the Greek philosopher, Hippasus (several centuries later, 5th Century BCE).