According to the files on the Majini, it is stated: "The parasite attaches itself to a human host, and is assimilated by the central nervous system. Infected humans lose all rational thinking facilities and are wholly subject to control by another type of Plaga known as control Plaga (usually another infected human). Hosts may lack rational thought function, but they still retain human-level intelligence such as the ability to understand and communicate with each other. They can use tools and are surprisingly crafty when working in groups against an enemy. Also, they are able to operate motor vehicles and heavy firearms."
Similar to the Ganado Plaga from Resident Evil 4, they inhabit the spinal column and enter the host's body through the throat.
There are three common types of Majini: the Town Majini, the Wetlands Majini, and the Base Majini.
- Town - Dressed in short sleeve shirts and khakis, these Majini are the weakest of the three. They make their cinematic appearance in chapter 1-1, but are replaced at the end of 2-3, returning in chapter 3-2. Some of these Majini choose to arm themselves with menial items, such as wrenches, bottles, crude clubs, gardening tools, and axes.
- Wetlands - A new twist on the traditional Majini, these members of the Ndipaya tribe are dressed in ancestral tribal skirts and war paint, and wield spears and shields. Some are mutilated from the parasite, with exposed sinew or missing lips. They are very athletic, able to leap several feet in the air, and can recover from blows very quickly. They make their appearance in chapter 3-1, and are never seen again after 4-2.
- Base - The final and most powerful of the Majini, these soldiers are far more intelligent than their predecessors, able to hide against walls and flush out their opponents with frag and flash grenades. They are dressed in military jumpsuits, never hesitating to clad themselves in heavy armor. They come armed with AK-74 assault rifles that feature green targeting lasers, while others arm themselves with stun rods, riot shields, and in some cases, rocket launchers.