Mutants that fell through the cracks, but not as far as the Morlocks.  Generally shunned because of their mutations, they ended up finding each other under the leadership of Rumble.  Current whereabouts are unknown.
Rumble: Former Xaviers student, leader of the Posthumans. Student Profile.
Gar: Green-skinned teenage boy with the ability to change in height anywhere from ten inches tall to over nine feet tall.  Generally considered the moral center of the Posthumans, as well as the calmest.  Dating Chill
Chill: Alabaster-skinned girl.  Radiates a cold aura around her, and can focus her abilities into a ‘cold touch’ that can send a person into hypothermic shock. 
Diva:  Short girl with small soft feathers over her skin.  She can influence people with her voice (very much like Lorna).  While not the most violent, probably the most zealous of the group.
Stab:  Angry teenage boy.  His fingers are as sharp as knives, and he often cuts himself or anyone else just by accidentally touching them.  The angriest of the group.
Clockwork:  His conscious can inhabit machines of any type.  His real body is whereabouts unknown.
Whisper:  Former Frost Academy Student.  Whereabouts Unknown.