Singularity

A singularity was a point in spacetime which could exist only inside a black hole. (TV: The Three Doctors) Romana described it as a mathematical point with no dimensions. (TV: The Horns of Nimon)

When Omega was transported through a black hole into the anti-matter universe, he gained control of the singularity and used its vast power to create his own world. (TV: The Three Doctors)

In 2003, the Seventh Doctor used a singularity which generated X-ray pulses to sterilise Agent Yellow, saving humanity at the cost of killing millions. (PROSE: Eternity Weeps)

In 2157, IMC planned to use controlled singularities to remove Lucifer's outer atmosphere, allowing them to mine the heavy elements at its core. (PROSE: Lucifer Rising)