The saddest moments in TV

I have been re-watching The West Wing, and I just watched the episode Posse Comitatus. It makes me cry every time. It got me thinking about the other episodes that have left me utterly inconsolable.

(WARNING: There could be spoilers here for Futurama, Angel, Sports Night, ER, SG1, & The West Wing). ( The saddest moments: My answers )

So, in your opinion, what are the saddest moments in television?