Krarg

Krargs were creatures made of crystallised coal. They were large, strong, semi-intelligent lumbering creatures with vivid red eyes. They were able to withstand high amounts of energy and could burn with a touch. When more Krargs were needed, they were created in large vats of heavy green gases that solidified coal over a skeleton. They had space carriers with smaller ships that could possibly become invisible. They were used by Skagra as his own personal army.

_{Biography from the TARDIS Data Core article, licensed under CC-BY-SA}