20 Great Horror Roles Ruined By Terrible Acting

Dr. Susan McCallister had a lot of potential. A Victor Frankenstein-esque character, McCallister is a hubristic scientist whose obsessive quest to cure Alzheimer's leads her to conduct dangerous experiments on a group of Mako Sharks, turning them into super-smart, ultra-lethal killing machines who go after McCallister and her team of researchers. 

She's an interesting character on paper, and to be fair, some of this potential does come through in the film. After all, you wouldn't normally expect the lead of a big-budget B-movie to be this morally ambiguous. Unfortunately, they cast Saffron Burrows in the role - big mistake. 

Through her relentlessly wooden performance, Burrows makes the character morose, charmless, and a total bore. McCallister ideally should've been a character where viewers would at least understand her motivations despite her unethical actions, but instead, she's out-and-out unlikable. In fact, test audiences disliked the character so much that Warner Bros. actually reshot the ending of Deep Blue Sea so that McCallister died in the climax, which was a wise move. 

With a better actress in the part, perhaps this character wouldn't have been quite so insufferable. Saffron Burrows really was lucky not to get a Razzie nod for this.