In the IDW continuity, Madame Null is the CEO of The Null Group, a business conglomerate with its hands in many ventures and ties to other dimensions. The Null Group previously sought to create and exploit mutants for profit, experimenting with hybrid combinations until the Mutanimals forced them to halt their work. Notably, The Null Group created Mutagen Man, Sally Pride, Man Ray, Zodi and Dreadmon.
Null was the primary antagonist of the Teenage Mutant Ninja Turtles: Mutanimals mini-series but her exact nature is still ambiguous. Her appearance definitively sets her apart as either non-human or no longer human, as do her condescending remarks regarding her many perceived weaknesses of the human race. She is highly durable, surviving a direct hit from a rocket-propelled grenade strike, although she was at least injured and temporarily stunned. She can also drain the life force of someone through contact.