2. Crispin Glover/Jeffrey Weissman - George McFly
Back to the Future's George McFly is one of the most brilliantly nerdy characters ever committed to celluloid, partly because he's played by the naturally insane Crispin Glover, and partly because his juxtaposition with Michael J. Fox is so strong, the laughs are practically guaranteed. It's a shame, then, that financial disputes prevented Crispin Glover's return to the second installment in the franchise, given how crucial he was to the success of the original flick. In what was something of a ridiculous and partly unfair move, the filmmakers went the opposite way that they did with the Elizabeth Shue situation - they opted to cast somebody that sort of resembled Crispin Glover, and, uh, could sort of act like him, too? This forced likeness, courtesy of one Jeffrey Weissman, was so strong that a lot of people didn't notice the switch: Zemeckis purposely shot Weissman so that people might have believed he was actually Crispin Glover. But it was a tacky play, and one that didn't pay off: Weissman is no Glover.