#5 The Host (2006): Giant creature shows up, kills people, hero and crew sets out and burst it open thanks to some valiant sacrifices. That's every monster story ever told in a nutshell. But here, the creature is ugly as sin. We have no idea if the hybrid thing, created by chemicals released into sewers, is a lizard, fish, tadpole, squid or something else. It's nasty and slimy.