National Institute of Mental Health

The National Institute of Mental Health ("NIMH" or "N.I.M.H." for short) is the Big Bad of the 1971 children's book Mrs. Frisby and the Rats of NIMH by Robert C. O'Brien, and the overarching antagonists of the Secret of NIMH movie series based on the book. It was based on the American federal research institute of the same name. Being a medical research institution, they often experimented on animals, often showing little regard for the welfare of their subjects. That said, how evil they are depends on how the viewer considering their experiments did result in animals developing human-like traits.