XVIII; Spanish: Gregorio XVIII; born Ginés Jesús Hernández y Martínez; 1 July 1959), also known by the religious name Sergio María de la Santa Faz, was previously the third Pope of the Palmarian Catholic Church, who in this capacity, claimed to be the 265th Pope of the Catholic Church from 15 July 2011 until his abdication on 22 April 2016.

According to Professor Magnus Lundberg, of the University of Uppsala, Hernández abdicated from his papacy on 22 April 2016 and was succeeded by Odermatt, who took Peter III as his papal name.

[3] Following his abdication, Hernández told El País that the Palmarian Catholic Church "was all a hoax from the beginning" to profit from believers and supporters of the alleged apparitions of Our Lady of Palmar.

[11] On 10 June 2018, Hernández and his wife, Nieves Triviño, climbed over the high walls of the Cathedral-Basilica of Our Crowned Mother of Palmar.

[14][15][16] On 17 May 2019, Hernández and his wife were found guilty of all charges and sentenced to six and five years in prison respectively and to pay a 35,000 euros fine to the two Palmarian Catholic bishops they injured.