Gender

Gender is mostly irrelevant in Crawl, but does appear in a few minor cases.

Players

Player gender is entirely irrelevant, and the game does not even allow the player to specify one. Should you wish your character to be definitively one gender or the other for (non-gameplay) role-playing purposes, choose a masculine/feminine name. This can be a problem on public servers, where all characters of a particular player have the same name.

Monsters

For the most part, monsters are neuter, merely being referred to as 'it'. This includes humanoid monsters that would normally have an explicit gender, such as humans and elves. A few monsters are established as male or female though. Most notably, virtually all unique monsters have a definite gender. Also, some monsters that are in their source mythology always one gender are referred to as such in Crawl, most notably sphinxes, harpies, mermaids, sirens, and water nymphs.

Monster gender is purely cosmetic; there are no effects of any sort that are affected in any way by gender.

Gods

By convention, Crawl's gods are neither male, female, nor neuter. Rather, every message and description about the gods is meticulously constructed to avoid using any personal pronouns, leaving their genders a matter of complete ambiguity. In fact, a message referring to an explicit gender for a god would be considered a bug by the developers.

That being said, in common conversation among players, the gods generally are given genders, if only for convenience. Most notably, Lugonu is invariably referred to as female. This dates back to her first introduction, where her working title was, in fact, Lucy. Other gods that are frequently referred to as female include Sif Muna and Elyvilon; most others are generally referred to as male by players.