Voord

The Voord were a malevolent race native to the planet Marinus which were immune to the peace-influencing powers of the machine known as Conscience. The Voord, under the leadership of Yartek, undermined Conscience's peace for 1300 years, until they attempted to take Conscience itself for their own. Tricked by the First Doctor into destroying Conscience, the invading Voord were destroyed, and their control over Marinus shattered.