Excrothian

The Excrothians were a species from the planet Excroth. Their civilisation was based on the principles of peace and enlightenment. When they started developing time travel, the Unon demanded the research to be stopped and destroyed the planet using a Dalek-made entropy engine when the Excrothians refused. The escaped survivors were forced to use robot-like walking tanks and started calling themselves Lect after the name of their ancient god of war and revenge.

The Lect caught the Ninth Doctor, Rose Tyler and Jack Harkness when they came to visit Excroth. Later on Fluren's World, the Lect came into conflict with the Unon. (COMIC: Weapons of Past Destruction)