Bissu is one of the five genders of the Bugis, an Indonesian ethnic group. There are divergent theories regarding the definitive origins and meaning of "gender transcendent", as the bissu are commonly called.
To be considered bissu, all aspects of gender must be combined to form a whole. This can include those who are born intersex. However, being bissu does not necessarily mean one does not possess only fully functioning male or female sexual organs, or even that one would not be called a cisgender male or female outside of Bugis society.
The role of the bissu (along with the other gender roles not normally found in Western society) exist in Bugis society because it is a cultural belief that all five genders must harmoniously coexist.
The advice of bissu is typically sought when a particular approval from the powers of the batin world is required. This may, for example, be the situation when a Bugis person is departing Sulawesi for the Hajj, the compulsory pilgrimage to Makkah. In that situation the bissu will permit an excellent djinn to seize them and to proceed as an emissary of the batin.
This is not in keeping with traditional Islam, but it has been tolerated by the regional Muslim establishment on condition that it does not comprise any act that is evidently in opposition to the Sharia. In this exceptional case, it means that the spirit and the Bissu's powers should not be measured as in any way autonomous from Allah’s power, because he is the only one who is to be venerated.