According to UESP, there are a total of sixteen races in Skyrim - ten playable, six non-playable:
All other races in the game are classified separately as Creatures.
For almost all of the above races, there are clear male and female varieties. The one possible exception among those is Dremora - all the ones I've seen could most closely be defined as male, although they may in fact be gender-neutral.
Some of the Creature races seem to also have gender-specific appearances.
- Lower-level Draugr appear to have male and female varieties.
- Hagravens appear exclusively female.
- Giants appear exclusively male.
- Flame Atronachs have a distinctly feminine appearance.
- Ghosts come in male and female forms.
- Wispmothers are exclusively female.
- Spriggans come in female-specific and male/gender-neutral varieties.
My question is this: In the guts of the game, where perk and blessing effects are calculated, do Creatures actually have a gender? Are there more Creature races which are considered to have gender affiliations, in addition to the obvious ones I've noted here? Or are all Creatures, regardless of appearance, considered neuter?