Halldon

The Halldons were a race of powerful beings responsible for the creation of the Daleks.

History
The Halldons engaged in a temporal skirmish with the Eternals, which ended with the Time Lords stepping in to put an end to the universe-threatening hostilities. This was one of the only two time wars in which the Time Lords had engaged before the start of their Great Time War with the Daleks themselves, which would end in their destruction. (PROSE: Meet the Doctor)

Per Bryant Anderson's findings, the Halldons conducted a scientific experiment in which they transplanted prehistoric Earth humans to the barren planet Ameron and artifically accelerated their evolution. Within two hundred years, the Halldons' test subjects had advanced to such an extent as to build fearsome weapons which frightened even their Halldon masters.

Realising the experiment was spinning out of control, the Halldons attempted to wipe out the Ameron humans, only for them to defend themselves and retaliate to the point of completely exterminating the Halldons. Free to advance unhindered, the evolved humans, determined to ensure their own survival, continued to evolve and eventually became the Daleks whom the Earth humans feared so greatly. (PROSE: We are the Daleks!)

The Brothers of Hame were descendants of the Halldons. Having learned from "early mistakes in genetic acceleration", the Brotherhood gave greater kindness in their accelerated evolution experiments which created the Forest of Cheem. (PROSE: From the Platform One Guest List)

Legacy
On Ollendorf 2, Bryant Anderson discovered the story of the Halldons as the true origin of the Daleks, but found it too horrific to share with his fellow humans. the Doctor discovered these unpublished writings next to Anderson's own corpse and the remains of a Dalek. (PROSE: We are the Daleks!)

Other, contradictory accounts of the creation of the Daleks existed. Reconciling these accounts, one group of historians theorized the Halldon might have transplanted the early humans onto prehistoric Skaro, with the various humanoid races of Skaro being descendants of those humans. (PROSE: The Dalek Handbook, Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)