The Missionaria Protectiva was a branch of a fictional organisation in the Dune universe created by Frank Herbert.

The Bene Gesserit practice "religious engineering" through a department called the Missonaria Protectiva; which was detailed to spread certain types of religious myth and superstition among the population of the Imperium , so that the Bene Gesserit could manipulate the populance to achieve their ends.

The Bene Gesserits plant legends and prophecies throughout the universe of messiahs and pivotal figures to come. There are two purposes to this. First, a Bene Gesserit in need can take advantage of the prophecies by fulfilling them, casting herself as a guide, protector, or some other figure, in order to manipulate the religious subjects for her own protection or purposes. Second, religion is a powerful force in human society; by controlling religion, the Bene Gesserit have a manipulative lever on society in general.

In the most inhospitable of environments the Bene Gesserit plant the Mahdi legend. The Mahdi legend is reserved for only the harshest environments, where a Bene Gesserit would need the maximum leverage over their environment.

In Dune Paul Atreides and Jessica Atreides were able to make use of these carefully planted myths among the Fremen in order to find refuge after the fall of House Atreides on Arrakis. Paul claimed the role of Mahdi, a legend planted among the Fremen by the Missionaria Protectiva. Paul Atreides indeed managed to use these myths to achieve religious leadership of the Fremen exploiting the vacuum left by the death of Liet-Kynes and used the Fremen to overthrow the Emperor of the Imperium.