Dr Lillith the fractured temporal villain
A product of a chroniton accident caused by Time Lord sending Dr Lilith (Sphereport) back in time during a field test of the Sphereport Temporal Dislocation apparatus.
The Nihilist is actually 12 alternate Dr Liliths’ with Sphereport’s memories of the future from Time Lord. Whether this can be undone or not is unknown.
She is currently in the custody of the NSI.