Terminus

Terminus was a a space station located (curiously) at the exact known centre of the universe. (DW: Terminus)

Terminus was used by a company to treat Lazar's Disease, the treatment involved using the radiation from Terminus's engines in uncontrolled doses to remove the disease often with a lethal amount of radiation. (DW: Terminus)

The Doctor theorised that if Terminus' engines were engaged in their weakened state (after millions of years of leaking radiation) they could potentially end the universe. (DW: Terminus)