Arnora was mother superior of the Unon.
After the Last Great Time War, Arnora and the Unon became time and space's "judge, jury and executioner". She led a crusade against the Excrothians for that cause and ordered the destruction of Excroth.
She trapped the Ninth Doctor in a sub-dimensional void after he tried to summon the Unon for answers. Whilst there, she probed his mind to discover how he survived the Last Great Time War, but eventually gave up. She tricked the Doctor into being brought to the planet Traxis to heal a time fissure. Arnora tried but failed to prevent the Lect Prelon Marleth from destroying the Perpetual City using Unon's own entropy engine, whose defences Marleth penetrated with the help of the Doctor. Arnora was killed by the fatally wounded Marleth. (COMIC: Weapons of Past Destruction)