Mantrid & His Divine Shadow
His Divine Shadow is not someone you'd want to take for a quiet drink down the pub. His Divine Shadow had the Lexx built, destroyed at least 100 worlds, killed Kai and all his people, tried to exterminate all the humans in the League of 20,000 planets, killed everyone who didn't agree with him, and generally went around pillaging, murdering and doing all sorts of nasty things to people. He is an essence that can be passed from host to host and is therefore almost immortal. The brains of the people who have housed his essence are preserved and known as the Divine Predecessors. He has ruled the League of 20,000 planets for at least the last 2,000 years.
Mantrid is a bio-vizier - one of those chaps who meddles where he shouldn't.  He was imprisoned on an ice planet for pissing off His Shadow in some way and is responsible for the reanimation of the insect that Kai found at the Cluster.  After the events of  "Mantrid" he became a human/insect/machine hybrid intent on universal destruction.  Literally.