Gods of Ragnarok

Raag, Nah and Rok, also known as the Gods of Ragnarok, were three beings who made sentient beings die for their entertainment.

The Gods were originally Old Ones were from the time before the creation of the Universe. They possessed the ability to exist in multiple times and dimensions simultaneously. (NA: All-Consuming Fire)

Rassilon speculated that the Gods had created and destroyed many universes. (PDA: Divided Loyalties)

They created the Land of Fiction as a diversion but grew bored and abandoned it. (NA: Conundrum)

They existed for a time on the planet Segonax where they took over the Psychic Circus and its entertainers, the Ringmaster and the Chief Clown. Outside their own world, they appeared as a man, a woman and a little girl sitting in the audience, while in another world they appeared as trio of living stone statues. They used the Circus to recruit new performers; if they were not pleased by the performance, they would reduce the performer to ashes.

The Doctor traveled into their realm and, using an amulet, reflected their own power against them. The stone forms of the gods broke apart and the Psychic Circus exploded, breaking the Gods' link with the normal universe. (DW: The Greatest Show in the Galaxy)

Behind the scenes
The Gods of Ragnarok's name is from the Nordic Ragnarök, which is often misunderstood as the "End of the World" or Armageddon. While an important part of Ragnarök is a climactic and cataclysmic battle, it ultimately ends with the renewal of the world as new and fertile.
 * One translation of Ragnarök is "the End of the Gods"; thus; the Gods of Ragnarok are "The Gods of the End of the Gods". This could be interpreted either as nonsense or an added layer of meaning.