Process Church of the Final Judgement

The Process Church of the Final Judgement, also known as the Process Church, was a British religious group established in 1966 and disestablished in the 1970s. Its founders were the British couple Mary Ann MacLean and Robert de Grimston, who spread the group's practices across parts of the United Kingdom and United States in the late 1960s and early 1970s. The Process Church's beliefs have been described as "a kind of neo-Gnostic theology".

MacLean and de Grimston initially met as members of the Church of Scientology in the early 1960s; the duo were ejected from the Church in 1962 and married the following year. They started a brief Scientology splinter group named Compulsions Analysis, which incorporated new religious elements; this developed into the Process Church, which was established in London in 1966. Its members initially lived in a commune in Mayfair, West London before moving to Xtul in Mexico's Yucatan peninsula. They later established a base of operations in the United States in New Orleans. Prosecutors investigating the Los Angeles murders committed by the Manson Family in 1969 suggested that there were links between Charles Manson and the Process Church, and despite the connection being unproven, the allegations subsequently damaged the Church's reputation.

Authors who have written about the group include Ed Sanders, journalist Maury Terry, and in the early 1970s, the sociologist William Sims Bainbridge. In 1974, MacLean and de Grimston separated.