Board Thread:The Panopticon/@comment-4028641-20151101035254/@comment-5918438-20151226180025

Zygon (Osgood) could not feasibly refer to Bonnie (The Zygon Invasion) any more than UNIT soldier (The Three Doctors) could refer to Palmer (The Three Doctors) or John Benton, also UNIT soldiers in that story. But UNIT soldier is the unnamed UNIT soldier, and we have names for those other two, and "UNIT soldier" is what we're given in the credits. For Name, all we're given in the credits is "Zygons", played by Aidan Cook and Paul Kasey (those are the actors who played Zygon Osgood, Zygon Kate, etc, whenever they were not in "human" form). Unlike UNIT soldier, though, we cannot simply name her Zygon (The Name of the Doctor) and be on our way—because there are many, many many Zygons in The Name of the Doctor.

Therefore, we have to go beyond standard disambiguation conventions. (If there's no other way to separate them, we even allow titles like "Mr" and "Mrs" to enter into titles because two people known only by that last name appeared in the same story.) Starting from the name Zygons, given in the credits to include all the "unmasked" Zygons throughout the story, we can only really do:
 * 1) Zygon (horse)
 * 2) Zygon (Elizabeth)
 * 3) Zygon (Osgood)
 * 4) Zygon (Kate) or Zygon (Kate Stewart)
 * 5) Zygon (McGillop)