Hyperon

Hyperon, also known as Hyperion, (PROSE: Doctor Who and the Genesis of the Daleks) was a planet which sent a fleet of war rockets to intercept a Dalek invasion of Venus in the Space Year 17000, as the Fourth Doctor recounted to Davros. (TV: Genesis of the Daleks) The Time Lords in the Time War understood that the Hyperon combatants were able to design warships which were resistant to Dalek firepower, allowing them to wipe out the Daleks' task force. (PROSE: Dalek Combat Training Manual)

Behind the scenes
For the charity stage play The Trial of Davros in 2005, a sequence called "space year" was shot depicting Hyperon intervention against the Daleks with Jeremy Bulloch portraying Chairman Skellon.