The most powerful person in the Star Wars universe is arguably the Father. He's over a million years old; a Celestial who lives on Mortis with his children. His daughter represents the Light side of the force, and his son, the Dark side. He is the embodiment of the Force, which is honestly the best way to describe him as. By killing either of his children, you completely upset the balance of the Force, and he is far more powerful than either of them. He has the power to bring people back from the dead, to stop time, to completely wipe memories, and to live eternally, among far more powers and abilities