Doomsday weapon

The Z-Bomb was an example of a doomsday weapon developed on Earth by 1986; with two or three placed at strategic positions around the globe, they had the potential to split the planet in half. (TV: The Tenth Planet)

In an attempt to intimidate John in 2050, K9 Mark 2 claimed to possess a doomsday weapon. (TV: The Custodians)

On Uxarieus, the Uxarieans devloped the Doomsday Weapon. (TV: Colony in Space)