Who will judge the 12th tribe of Israel? I was reading the Last Supper passage in Luke the other day and came across this verse:


  Luke 22:30 (KJV)
  30 That ye may eat and drink at my table in my kingdom, and sit on thrones judging the twelve tribes of Israel.


Jesus tells the 12 disciples that they will judge the 12 tribes of Israel. Since I assume Judas Iscariot will not have this privilege, who will judge the 12th tribe of Israel?
Why are you assuming a one to one correspondence? The Greek here says "y'all" will judge them. The idea is that collectively you will bear witness against all of Israel. 

In Greek, the verse is:


  ἵνα ἔσθητε καὶ πίνητε ἐπὶ τῆς τραπέζης μου ἐν τῇ βασιλείᾳ μου, * καὶ καθήσεσθε ἐπὶ θρόνων τὰς δώδεκα φυλὰς κρίνοντες τοῦ Ἰσραήλ.


κρίνοντες is a verb (to judge - from which we get 'criminal') which is in the 2nd person plural, meaning that "You" is "y'all" (aka plural) and not singular.

If you need a one to one correspondence, take your pick between Matthais or (my personal bet as the real 12th apostle) Paul. But there's no reason too. 

One person can judge multiple people, and multiple people can judge one.