Kraarn

Kraarn of the Kraagaaron was said to be one of the most evil beings in Mutter's Spiral by Zargath, he had laid waste to whole solar systems and enslaved entire species.

He had been defeated by the Doctor, and intended to ally with other aliens at Research Base Truro to eliminate him. While outlining his strategy, he involuntarily caused an electrical surge, which killed him on the spot. (COMIC: Death to the Doctor!)

Behind the scenes
In an interview with Jonathan Morris released in The Widow's Curse the description for Kraarn was given as; "wearing a dark space-suit uniform. His skin is mottled and glowing like lava. His head is bald, and resembles a leering skull. He is totally creepy". However, the lava aspect was dropped as it was deemed too similar to the Pyroviles from The Fires of Pompeii.