Lead actors who were not even believable in their role for one minute
I nominate Naomi Watts in "Fair Game." Critics praised her performance, but I never forgot I was looking at an actress. She couldn't utter any of her lines convincingly.
Jennifer Lawrence in virtually every role up to date. Seriously. She's plays HERSELF in every one of these movies. I can't wait until 2015 when the Hunger Games films are over and I'd no longer have to hear about her.