Children of Kasterborous

The Children of Kasterborous were a group that Pallant theorised the inhabitants of the Needle were of before they lost their memories. In his theory, the Children of Kasterborous were Gallifreyan/Human hybrids who pursued interventionist policies to create a new age of universal peace, but failed and were condemned to live until the end of time in the Librarinth. (PROSE: The Infinity Doctors)

Earlier in its existence, the Needle had been ruled by a Gallifreyan Imperial Family. (PROSE: Father Time)

Behind the scenes

 * Author Lance Parkin wrote several drafts of the epilogue to The Dying Days, which was to show Jason Kane being dropped off on Dellah by the 42nd Doctor and his wife Iphegenia. Two of the drafts, respectively entitled The Last of the Time Lords and Valeyard of the Daleks, were later published in fan publications and on Parkin's blog. Both of these drafts mentioned that the "Children of Kasterborous" allied with humanity in the Final Dalek War, which eventually drove the Daleks to their ultimate extinction.
 * Parkin's reference book Whoniverse: A Guide specified that the Children of Kasterborous were the heirs of the four surviving elementals.