Enmerkar

Enmerkar (fl. c. 2750 BC) was an ancient Sumerian ruler to whom the construction of the city of Uruk and a 420-year reign was attributed. According to literary sources, he led various campaigns against the land of Aratta.

He is credited in Sumerian legend as the inventor of writing. An excerpt of an ancient text states, "Because the messenger's mouth was heavy and he couldn't repeat (the message), the Lord of Kulaba (Enmerkar) patted some clay and put words on it, like a tablet. Until then, there had been no putting words on clay." This is the earliest known story in history about the invention of writing.

Source: Wikipedia — https://en.wikipedia.org/wiki/Enmerkar