The Ones were a family of exceptionally powerful Force wielders who lived on the planet Mortis during the Clone Wars. Led by the Father, the Son and Daughter. Who were embodiments of the dark and light sides of the Force, respectively. The Son and the Daughter were worshiped as the Twin Deities or simply as the spirits in the Nightsisters‘ religion.
In the release of «Star Wars: The Clone Wars The Complete Season Three» in DVD and Blu-ray, during the featurette of the episode: Ghost Of Mortis, Dave Filoni explains how Darth Revan, and Darth Bane almost get into the episode, since George Lucas was: «looking for two ancient Sith lords that, you know could bring some meaning, like a upper evil influence guiding The Son» ―Dave Filoni but that at the end, George Lucas retracted this decision due to how the Sith interact with The Force. Therefore, that scene with Revan, and Bane, wasn’t possible. Dave Filoni also explained the importance of George Lucas‘ intensive involvement in this arc, due to the extensive relation with the different aspects of The Force that it has, and how important it was for him and the crew to get all of what was presented in the arc, right.