Trans*/Transgender: Someone who does not identify with their sex assigned at birth.
Two Spirit: Someone who fills one of the many mixed-gender roles prevalent in Native American communities.
Transfeminine/Transmasculine: Someone who identifies more female than male or more male than female.
Multigender: Someone who identifies with more than one gender (e.g. bigender).
Trans Man/Trans Woman: Someone who was female at birth but identifies as male/someone who was male at birth but identifies as female.
Gender Fluid: Someone whose gender changes.
Agender: Someone who does not identify with a gender.
Genderqueer: Someone who does not identify within the gender binary.
Identities Not Under The Trans* Umbrella:
Cisgender: Someone who is not trans*.
Drag performer: Someone who wears flamboyant clothes for entertainment value (can be trans*).
Crossdresser: Someone who wears clothes associated with the/a different gender (can be trans*).
Intersex: The presence of a less common combination of biological features that generally distinguish male and female (can be trans*).
From Trans Student Equality Resources