11. River Song Revealed Doctor Who ('A Good Man Goes To War')
This cut was the ending to the midseason finale during season six of 'Doctor Who'. The Doctor has failed to rescue Amy and Rory's baby daughter from the nasty baddies, but all hope is not lost, when River Song whispers her secret into the Doctor's ear and he runs of in the TARDIS, giggling with delight. Amy is confused, but River clears things up (sort of) with a massive bombshell: she is Amy and Rory's daughter! Whaaaa? It's a time travel show, so this sort of thing is to be expected. Amy's reaction then cuts-to-black, and a message that "the Doctor will return". Of course, this is not the only instance of cut-to-black in 'Doctor Who', especially in the modern series, but it stands out as being of particular impact, considering the mystery of River's true identity had been taunting us for two seasons already! Such a shame that it was all downhill from there...