The folks in this odd quartet are the four main leaders of the Underdark - a subterranean realm where weird creatures congregate. From left to right, we have...

Boss Rio Margot ("The Madonna of the Lotus")
Domain: Mother & Child Bloc
Backstory: When the goddess Tara wept for the suffering of all life on Earth, her tears fell upon a colony of metamorphosing butterflies and the resulting insects joined together to form Rio Margot. Equal parts matriarch, warlord and pop icon, Rio Margot fought many battles in her pursuit of a beautiful society centered on herself. Her private pursuits include animal welfare and martial arts: she keeps her own private farm and is the only living master of the poisonous Buddha's Palm technique.

Dr. Dammitall ("Creepy WALL-E Knockoff")
Domain: Godhead Bloc
Backstory: A tinkerer spent her life building a remote-controlled robot from an old fortune-telling mannequin, and upon the creator's death, her accumulated adoration for the toy imbued it with life. Seizing control of his territory through guile and ambition, Dr. Dammitall (a title he legitimized by awarding himself a doctorate) set up a secure but totalitarian haven for robotkind. He spends his days building more of his folk, outfitting himself with hidden weapons, and losing at chess.

Boss Slash Tomorrower ("The Monarch of Monsters")
Domain: Fish Head Bloc
Backstory: Slash began as a discarded character concept for a popular children's TV show, whose trashed sketch was exposed to ideal mutation conditions in the city junkyard. Springing fully-formed from the page, he easily established himself through his need to dominate. He's mellowed since his conception, becoming a lazy ruler and father of 25 identical princelings, but will readily attack anything resembling a Power Ranger. Not featured is his weapon of choice: the 6-String Axe.

Boss Tonguetied ("The Silken Garrotte")
Domain: Deep Down Breaker Bloc
Backstory: The dark secrets and lies of an underworld family took on a life of their own, becoming anthropomorphized in the suit of a hitwoman. As a result, the ever-insatiable Tonguetied loves intrigue and craves secrets. His domain is a network of shadowy closets and lamp-lit boudoirs, providing ample means for him to spy on his subjects. In addition to his aspirations as a mover and shaker, he's the friendly rival of Dr. Dammitall and frequently beats him in chess matches.

 rogus247 created this.
 Readasaurous commissioned this for me. He owns Tonguetied, and was instrumental in establishing Slash's design.