Dionicio Castellanos Torres (born May 19, 1971) is a Mexican professional wrestler best known by the ring name Psicosis (sometimes Anglicised as Psychosis). Castellanos has performed for Asistencia Asesoría y Administración (AAA), Consejo Mundial de Lucha Libre (CMLL), Extreme Championship Wrestling (ECW), Total Nonstop Action Wrestling (TNA), World Championship Wrestling (WCW), and World Wrestling Entertainment (WWE) as well as a variety of Mexican and American independent promotions. He was the shortest reigning WCW Cruiserweight Champion with a reign that lasted less than an hour. After leaving WWE, Castellanos has mainly worked under the ring name Nicho el Millonario.