8. Zoom Kills Barry's Dad - The Flash
2016 wasn't the strongest of years for The Flash. The show lost a lot of what made it so fun and fresh in its first year, with convoluted time travel elements and lacklustre villains.
However, the show - and in particular Grant Gustin - remained more than capable of selling an emotional gut-punch, and none came bigger than the death of Barry's father, Henry Allen.
Henry wasn't a consistent presence in Barry's life, due to being in prison for most of it, but the two had a touching bond (more than helped by the chemistry between Gustin and John Wesley Shipp).
The importance of Henry to Barry was repeatedly made clear, and we had a number of heartwarming moments between them. There was also the fact that Barry had lost his mother, something the series had repeatedly used as an emotional anchor (and revisiting it the episode before this happened).
Trying to drag Barry down to his level, then, Zoom does the one thing that'll work: he kills Henry in front of him. It'd been telegraphed, but nothing quite prepared us for the devasting loss.