Even ignoring the Red Wedding, I can't think of a deadlier TV show than Game of Thrones. Digg assembled this montage of every single death in the series so far, and the count comes to an unbelievable 5,179 — or over 172 deaths per episode.
You don't have to have read George R.R. Martin's books to guess that perhaps the killing doesn't stop after the events shown in season 3. So really, the only thing left to do is guess how high the death toll will be when the show finally airs its finale. Personally, I'm guessing it's going to hit six digits.