What type of question is "He's right behind me, isn't he?"

This sort of question He's right behind me, isn't he? is popular on comedy TV shows.

It's usually said by somebody just after they've been poking fun or talking badly about someone to group of other people. The group of people are all laughing at the butt of the joke/abuse and then fall silent. At this point the ringleader notices that the group has gone quiet and asks He's [the person being made fun of] is right behind me, isn't he?

It's not exactly a rhetorical question because the ringleader doesn't know for sure but they are very confident that the answer is yes.

I am asking if there is an English grammatical or linguistic categorization for this type of question. I'm not asking about the use of this type of question on TV or film or stage.

I now know what a tag question is, and this is a tag question but I would like to know if it also another type of question

It is very close to a rhetorical question but it isn't because it does matter what the person being asked replies.

I don't think it's a leading question because it's not really encouraging anyone to give either a yes or no answer that suits the person asking the question.

My question is: what category of question is this?

Answer

The answer to what type if question this is, in the sense that you are asking it, depends on how much information related to the answer the asker has.

If the asker has little information then this can be considered a closed, factual question.

If the asker has enough information that he should be able to surmise the answer this could be a rhetorical question.

Using the example above of a sitcom, if the speaker is speaking to one other person, and that person's face suddenly looks surprised while looking in a direction behind the speaker, that's probably not enough information to make the question rhetorical, so it's a simple closed, factual question.

If, on the other hand, the person listening puts one hand over his mouth, and with the other points rapidly over the speaker's shoulder, or, alternatively, if the person being spoken about let's out a loud "harrumph" then either of these could be enough information to make the question rhetorical.