"Human/person/individual" for a start. Reducing anyone's entire self to a very specific noun is deeply dismissive and disparaging, versus applying adjectives to an ubiquitous parent class (eg "person"). Compare eg, "that Jewish guy" / "that Jew", "that person who happens to be homosexual" / "that homo". Calling an individual homosexual vs calling them "a gay" isn't about being PC, it's about actually respecting them as a complex and complete individual and not just a stereotype or The Other.
"Ladyboy" is a completely culture-bound categorization that isn't to be confused with the Western (admittedly poor) understanding of transgenderism. If anything it's closer to the idea of drag.
http://en.wikipedia.org/wiki/Gender_identities_in_Thailand#Meaning_of_Kathoey.2FLadyboy
So asking "what is the PC term" is really unhelpful since it depends on greatly varying factors such as language, culture (since
many many cultures around the world and history recognize more than two genders and even sexes), and most importantly personal identity.
In the West at least, the majority of transgender (and transsexual) [umbrella often is written just as "trans*"] individuals are binary-identified as one male/female (or man/woman. Not necessarily at the same time, eg bigender individuals may live different parts or locations of their lives as a different sex or gender). So with most Western trans* folk, it's not unreasonable to guess that it's respectful to address them based on their (current) gender expression, eg "that man" or "that woman" and not as "that transsexual" or "that ladyboy".
A subset of the trans* umbrella is non-binary identified individuals who don't identify as any one particular sex or gender, eg agender, genderqueer, androgynous, genderf*** individuals, or identify as "third sex" or "third gender" (India is probably most famous for "third sex" individuals, often referred to as "kinnar" or pejoratively as "hijra"; the
Bugis culture in Indonesia recognize five genders). If hir gender isn't obvious to you, and you genuinely wish to respect hir, ask how zie would like to be addressed, but also don't feel like it's your right to know. "Them/they" can be acceptable, and isn't uncommon among non-binary trans* folk (since pronouns like zie/hir, ey/em,
and so forth, aren't very commonly known outside of non-binary communities). "It" is considered deeply disrespectful unless it is its preferred pronoun, in which case by all means respect its wishes but don't assume that same usage applies to anyone else.
Long story short:
- Adjectives (if at all), not nouns.
- When in doubt, ask respectfully how to address someone and do not secondguess their answer. Your consideration may make their day. If you try to guess and misgender them, you may ruin their week.
- Don't assume anyone's sex or gender is any of your business. Unless you're in an intimate relationship, how is it possibly relevant to bagging their groceries or depositing their cheque?
- Lastly, don't presume that it's their responsibility to educate or enlighten you about the nuances of trans* experience or such. Some folk love to explain gender theory and anthropology at length; other people just want to buy some damn groceries and go home.
Also, I can kill you with my brain.