Central nervous system atypical teratoid rhabdoid tumors are very rare aggressive tumor of childhood, primarily occurring at age of less than 3 years old. The prognosis of these tumors is very poor, with a reported median survival of 6-12 months in most cases. Treatment typically consists of aggressive chemotherapy and radiotherapy. We present the case of a 65-year-old man who presented with progressive encephalopathy and change in personality over 3 months period. The patient had further accelerated decline over 3 weeks. The diagnosis of atypical teratoid rhabdoid tumor initially remained elusive despite very extensive workup, but was eventually confirmed via open brain biopsy. To the best of our knowledge, this is the oldest reported case of atypical teratoid rhabdoid tumor in the literature. We further extend the spectrum of this rare disease.