5. Transformer-Girl Makes No Sense (Revenge Of The Fallen)
One of the weirdest introductions in the entire series is that of Alice (Isabel Lucas) in Revenge of the Fallen, a girl in Sam's college halls who appears to quickly fall for him, though is in fact a Decepticon in female form. Once she uses her feminine charms to force herself upon Sam, a robotic appendage appears from under her skirt (and why wouldn't it?), resulting in a scene of awkward confusion when Mikaela walks in on the pair (by which point Alice has hidden her contraption). The problem with introducing a Decepticon who can shape-shift into convincing human form is that a) it's a total Terminator rip-off and b) it makes audiences wonder why the Decepticons don't do it more often. If they ever need to stealthily kill off a human or just maintain a low profile, it's a pretty damn useful power, but once Alice is done with, it's never mentioned again. Not to mention, Alice made the age-old villain mistake of not just killing Sam when she had the chance, making her pretty damn useless anyway.