Hagoromo Ōtsutsuki

The was said to be the legendary figure who founded the ninja way and was the first to invent ninjutsu. He was said to be the only shinobi to posses the Rin'negan, which presumably laid the groundwork for the other dōjutsu, the Sharingan and the Byakugan.

As of now, the only other person to be known to posses the Rin'negan is Akatsuki's Pein. Weither this means that the Rin'negan is a unique Kekkei Genkai, that isn't passed down by blood, or if Pein is directly related to the Sage of the Six Paths is currently a mystery.