5. David Hasselhoff - Piranha 3DD
At some point in the distant past, David Hasselhoff decided to stop being a serious actor and simply become a gratuitous self-parody with extremely limited comic impact, but it was now so long ago, it's hard to pinpoint exactly where the two phases met. This year, the Hoff really hit a low-point, making regular appearances on Keith Lemon's panel show Celebrity Juice, in skits that were basically a step down from eating kangaroo's testicles on I'm A Celebrity Get Me Out Of Here, as well as appearing in the disgustingly bad Keith Lemon: The Movie in a completely expected cameo and in Piranha 3DD as himself as a celebrity life guard. Based entirely on the "joke" that Hasselhoff used to be in Baywatch, and was marketed as the actor "winking at" his own career (though they conveniently seem to have left out the fact that he basically did the same thing with greater effect in the Spongebob Squarepants Movie.) And this might have worked if Hasselhoff hadn't been self-parodying pretty much since Knight Rider disappeared, and no matter how much he might want us to laugh along with him, noone is laughing any more. It's all just a little sad.