A Reverend Mother is a fictional character appearing in the novel Dune, being a Bene Gesserit woman who has finished her training.

At the end of her training, the Bene Gesserit undergoes a ritual involving a significant amount of one of a class of awareness spectrum narcotics. The drug enters her body as a poison. If she survives this, by a conscious transformation of the drug on a molecular level to a non-poisonous substance, she gains the memories of all the preceding Reverend Mothers in her line, resulting in great knowledge and power. The particular narcotic used by the lines of Reverend Mothers on Arrakis is the Water of Life. The liquid exhalation of a sandworm produced at the moment of its death by drowning.

It is impossible for normal males to undergo this ritual, they will be killed. In an extensive breeding program, the Bene Gesserit tried to produce a male who could do this, the so-called Kwisatz Haderach. The final result of their program was Paul Atreides.

Paul Atreides sister Alia Atreides was accidentally transformed into a Reverend Mother inside the womb of Jessica Atreides resulting in a being even more powerful than the Kwisatz Haderach.