5. Edward Furlong
Here's one that's really disappointing. Edward Furlong was superbly cast as the precocious, young John Connor in Terminator 2, such that he seemed destined for a great career as an actor. After starring in a number of not-so-good trashy flicks (namely Pet Cemetary II), Furlong finally lived up to that early promise with a superb performance opposite Edward Norton in Tony Kate's devastating American History X, but after this it all started to go wrong. However, drug and alcohol abuse saw Furlong's career de-stabilise; he was fired from Terminator 3 despite the role being ready for him on a silver platter, and he began starring in increasingly desperate flicks like a particularly horrible sequel to The Crow, and even an Uwe Boll film called Stoic (though it was admittedly one of the infamously abd director's "best" films, all things considered). Nowadays, Furlong is reportedly destitute, unable to even pay child support, and has refused to go into drug rehab even though it would save him an impending jail sentence. He's also waiting to be brought up on charges for assaulting his ex-girlfriend, Monica Keena. Sadly, this is one story where I feel like we haven't heard the worst of it yet.