Originally Posted by
msb0b
The last Access Narita bus is at 22:50 and the last Keisei bus is at 23:15, which OP referred to in an update.
And Limousine Bus has buses to TCAT and Tokyo Station at 23:00 from Terminal 1. 22:55 from T2.
I think there is a later JR train to Chiba city but it won't allow for a connection to downtown Tokyo. Actually it only goes from Narita City at 23:30. The farthest you can get by JR seems to be Tsudanuma.