Tumu-nui is the name of several figures in Tahitan mythology.

In the creation myth of the Society Islands, Ta'aroa creates Tumu-nui and his wife Paparaharaha as foundations for the Earth.^[1] Ta'aroa commanded them to approach one another, but they both refused as each had a fixed place in the earth.^[2]

This is also the name of the uncle of the hero Rata. He was king of Tahiti. When he was lost at sea, his nephew Rata became king.