Gods of Ragnarok's universe

The Record of Rassilon speculated that the Gods of Ragnarok had come from a universe before the Great Old Ones' universe, and had been destroying every universe since. (PROSE: Divided Loyalties)

The quantum harvester believed that the Gods of Ragnarok came from a reality home to various death gods who had invaded the Doctor's universe, including the Beast, (COMIC: Cindy, Cleo and the Magic Sketchbook, Old Girl) who claimed to have originated from before the Doctor's universe. (TV: The Satan Pit)

Behind the scenes

 * In his notes for The Quantum Archangel, Craig Hinton asserts that the Gods of Ragnarok came from the universe before the Great Old Ones' universe, and were one half of that universe's Six-Fold-God alongside the Gods of Armageddon (Arma, Gedd, and Onn). Much like the Six-Fold-God of the Doctor's universe, they were the equivalent of the Time Lord High Council of their reality, with Hinton saying that one of the Gods of Armageddon must have been their universe's version of the Doctor. (Shelf Notes)