The One was an interstellar entity that built Vuffi Raa to explore the Galaxy and its civilisations. Together with an entity known only as The Other and an immense gathering of other entities known only as The Rest, The One was actually a droid manufactured by a starfish-like species who had gone extinct when the sun of their planet went nova. Their droids, however, "lived" on and eventually achieved full sentience.
Like others of his kin, The One was a tremendously powerful, starship-sized droid who was able to fly from one side of the galaxy to the next. His "son," Vuffi Raa, is presumably the first droid of his kind, as well as the first droid to be built by another droid of this extinct species instead of built by the species themselves.