Brother Adrian is an unseen character in Grand Theft Auto V. Adrian is the leader of the Children of the Mountain movement. The Cultstoppers website states he is a Welsh tax accountant. He is mentioned several times by Audrey between songs on Self-Actualization FM in Episodes From Liberty City. He also appears as a guest on West Coast Talk Radio and speaks with an Irish accent. He is derided by Lazlow Jones many times during the show, who calls him a "wackjob", "cultist" and "pervert". 

"Brother Adrian is an English mystique, spiritual leader, poet, musician, vegetarian chef, yogi, tax accountant, and expert in henna tattoos who, with little to no professional training, discovered the secret to realizing human potential, convention and seminar revenue, and utilizing completeness."