In Monty Python's Life of Brian, Reg was the leader of the People's Front of Judea. This answer is correct because the question specifically asks for the political organization that Reg leads in the film. The other options, Judean Popular People's Front, Popular Front of Judea, and Judean People's Front, are all organizations mentioned in the film but do not represent the group that Reg leads. Therefore, the correct answer is People's Front of Judea.