This has been something that's been on my mind for quite a while. With the rise of transgender rights, it has been brought to my attention that sex and gender are 2 separate constructs. Sex is biological and refers to chromosomes/genitalia, while gender is social/psychological and refers to how an individual presents themselves and how they want the world to see them. For this reason, the "male" and "female" categories should be based on how a character is presented, with the "genderless" category reserved for characters whose gender is ambiguous. The proposed "sexless" category would be for characters who are still identifiable as male or female but have no biological sex. Characters in the "sexless" category can be any gender and any species.