Shub Niggurath, also known as the Black Ram of a Thousand Young, is an antagonist that the Turtles face in Infestation 2, though referred to in-story with male pronouns. Shub Niggurath is brought forth by the cult leader, Bloch. Donatello discerns that this creature is actually some kind of vast, dying parasitical fungus that has festered under New York City for decades if not centuries. The Turtles manage to sever the veins through which it feeds, and then drop a giant idol on it to keep it from eating them instead.
In the 2012 TV series episode Fungus Humungous, the character Fungus Humungous is conceptually very similar to the IDW version of Shub Niggurath in that it is a giant fungus festering beneath New York City. But whereas the people and animals Shub Niggurath infects into serving it are deemed mutations, Fungus Humungous is itself explicitly a recent mutant created from spilled mutagen in the wake of the events of The Mutation Situation.