Others
Some languages have even more grammatical voices. For example, Classical Mongolian features five voices: active, passive, causative, reciprocal, and cooperative.
The antipassive voice deletes or demotes the object of transitive verbs, and promotes the actor to an intransitive subject. This voice is very common among ergative–absolutive languages (which may feature passive voices as well), but also occurs among nominative–accusative languages.
There are also constructions in some languages that appear to change the valence of a verb, but in fact do not. So called hierarchical or inversion languages are of this sort. Their agreement system will be sensitive to an external person or animacy hierarchy (or a combination of both): 1 > 2 > 3 or Anim > Inan and so forth. E.g., in Meskwaki (an Algonquian language), verbs inflect for both subject and object, but agreement markers do not have inherent values for these. Rather, a third marker, the direct or inverse marker, indicates the proper interpretation: ne-wa:pam-e:-w-a "I am looking at him", but ne-wa:pam-ekw-w-a "He is looking at me". Some scholars (notably Rhodes) have analyzed this as a kind of obligatory passivization dependent on animacy, while others have claimed it is not a voice at all, but rather see inversion as another type of alignment, parallel to nominative–accusative, ergative–absolutive, split-S, and fluid-S alignments.
Read more about this topic: Voice (grammar)