(Covers information from Anderson's universe)
Externally, they are not different from the standard zombie, yet they seem to possess a pale-greenish coloration, possibly a side-effect of their mutation. Internally, however, they are more of an archetype of the Majini, rather than the Ganados. As such, like the Majini, these type of zombies are able to run and possibly have gained higher intelligence from the Plaga.
Whether Plaga exist in the same form as in the games in the films is unknown. However, whichever their origin may be, Wesker also exhibits Plaga-like abilites when mandibles emerge from his mouth during his battle with Alice.
In the draft script for Afterlife, Luther and Alice speculate on the possibility that the T-virus has mutated wildly among the undead populace, allowing them to run, burrow underground, and even swim; the possible mutation in the T-virus is responsible for giving birth to the new undead whom attack their victims with flower-esque mandibles.
Role in Afterlife
The Majini Zombies first appear in the film when the camera is panning over the exterior of the prison that is surrounded on all sides by thousands of zombies; then, the camera travels underground and, for a few seconds, one of the Majini Zombie's faces is seen briefly. The Majini Zombies were also detected by Wendell when he told Luther West that he could hear "things in the walls". Shortly after, the zombies break through into the shower room, unnoticed by anyone.
They reappear when Alice attempts to take a shower and she catches Wendell, whom she thought was spying on her.
She attempts to force him out of the room at gunpoint when he pauses to look at her, and then he spots one of the zombies standing behind Alice when it viciously attacks and drags Wendell through their entry hole.
When Chris Redfield, Crystal, and Alice attempt to swim to the armory to obtain weapons and gear, followed by the zombies all the while; the zombies only reveal themselves when the trio reach the armory and one of them snatches Crystal, drags her underwater, and kills her before being stabbed by Alice. More and more start to arrive and despite a few being dispatched single-handedly by Chris, the two survivors are overwhelmed and the are forced to flee.
After Alice destroys a large group of zombies on the prison's roof and kills a few outside the main entrance with some assistance from Luther, the few survivors left (Angel Ortiz having been shot in the head by the traitorous survivor Bennett, Kim Yong having been sliced in half by the executioner, Wendell and Crystal having been killed by the Majini Zombies, and Bennett literally flying the coop in Alice's plane) attempt to leave out through the same hole the zombies dug, only to be ambushed and having Luther separated and presumed dead by the last three survivors.
Luther survived and was last seen emerging from a large sewer tunnel looking a little worse for wear; when two of the Majini Zombies appear he easily dispatches them and is witness to the multiple Umbrella ships descending on Arcadia, the last known infection-free haven for survivors.
Resident Evil: Retribution
The Majini Zombies reappear in Resident Evil: Retribution alongside another sect of undead, who appear have gained intelligence and the ability to use weapons against survivors. These zombies are also referred to as the Plaga Undead when the Red Queen releases them against Leon and his team. Later in the film, the evil clone of Rain Ocampo injects herself with the Plaga parasite and becomes nearly invincible before being dropped through ice into an ocean where a massive swarm of Majini Zombies are swimming up from the flooded Umbrella Prime facility and they devour her.