Which achievements are missable in Batman: Arkham City?
From what I've seen and gained, there is maybe only one that is missable. However, you will have a second chance to get it if you go through a New Game Plus to get that achievement.
Catch
This one is not related to the main story, and is related to another achievement Mystery Stalker. You only meet a certain person 5 times during the game, and after that they are gone. You have to throw a remote controlled batarang at them.