Anti-time
Anti Time
Anti-time is mentioned in Big Finish Productions' Doctor Who audio dramas. The canonicity of the audio dramas, like other Doctor Who spin-off media, is unclear.
In the audio play Neverland Anti-time is an other-dimensional realm which has inhabitants sometimes referred to as "Neverpeople". Some, if not all, of these people are Time Lords who were thought to have been executed for treason by the Celestial Intervention Agency. The device used for the executions, the Oubliette of Eternity, was supposed to erase the Time Lords from history but instead transformed them into Neverpeople.
The culmination of these events was the attempted destruction of Gallifrey by the Neverpeople by using a casket of Anti-Time. However The Doctor materialising his TARDIS around the Time Station protected Gallifrey from the impending destruction by containing the force of the anti-time explosion within the TARDIS. These events then led into the audio play Zagreus.
Zagreus documents the effects of anti-time seepage into the normal universe as historical anachronisms cause the Web of Time to break down. Both the Eighth Doctor and the TARDIS are "infected" by anti-time and/or its inhabitants, who harbor ill will toward the normal universe.