Narmer/Menes
It is not surprise that the first pharaoh of Ancient Egypt, who united the two territories of Upper and Lower Egypt and established the First Dynasty more than 5,000 years ago, is at the top of this list. Scholars continue to disagree over who he is, though.
In essence, Narmer and Menes are the only names we have to work with. Evidence points to either guy as the first pharaoh, albeit Narmer's case appears to be stronger. Since it was created during his lifetime, the Narmer Palette serves as a good illustration. In addition to naming Narmer, it also depicts him donning the crowns of both Upper and Lower Egypt.
The idea that Narmer and Menes were actually the same person has been debated among Egyptologists for a century. This idea isn't completely implausible because pharaohs were known by several names. Whatever his name, it is what he accomplished that counts, since the first pharaoh established a new empire that would go on to occupy a singular and indisputable position in ancient history.
Reign: c. 3150 BC (1st Dynasty)
Predecessor: Ka
Successor: Hor-Aha