3. Flint Marko Spider-Man 3
Who Is He?: A petty crook who turned to crime to fund medical treatment for his sick daughter, and became Sandman after falling into a particle accelerator.
Why Is He So Horrible?: He may only have turned to crime to help his daughter, but hes needlessly violent about it. Killing Peter Parkers Uncle Ben was an accident, but not beating up dozens of police officers and security guards (and possibly unintentionally killing a few) - his physical strength when in full-on sand form is pretty astounding after all, especially since his ability to turn to sand makes it easy for him to escape injury and infiltrate places without beating up everyone he sees. Not to mention that in the film's final act, he teams up with Venom with the explicit intention of killing Peter.
What Happens To Him?: He survives the final battle against Peter and Harry Osborn, apologises to Peter for Uncle Bens death, and then turns into a stream of sand and flies away.