5. Justin Hammer (Iron Man 2)
Justin Hammer was essentially the secondary villain in Iron Man 2 - with Whiplash AKA Ivan Vanko being the primary villain. Hammer didn't pose a physical threat to the titular hero, but he was his biggest intellectual and business rival who constantly sought to undermine Tony Stark - in this movie's case by recruiting Vanko to build better armoured suits than those belonging to Stark, in order to beat him to military contracts and destroy his legacy. What ultimately happens regarding Hammer is that he is embarrassed by Tony Stark who is more popular with the general public, more prudent and just outright better at what he does. Hammer was presented as something of a bumbling joke, as a result, and is used as comic relief (despite his obvious high intellect and affluence) and it would be great to see him return with a new found level of intent and adeptness seeking revenge - not least because Sam Rockwell who plays him is great.