This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Deep Blue Sea
Most of the shark kills, but one in particular: half of a guy is eaten... and then the foot twitches.
How about the lead scientist who was strapped to the gurney and used as an underwater Battering Ram by a shark to break the observation window? Made ten times worse by the fact that that he was not only still alive because of his oxygen mask, but awake. *shudders*
Pay attention to him, and you'll see him struggling to get off the gurney. He knows what's going to happen to him, he's visibly scared, and he can't do a damn thing about it. Right before impact you can see him close his eyes.