8. Agent Coulson - The Avengers
Coulsons death ultimately ends up being the driving force between the Avengers coming together, and its a great moment thats well-earned. Considering the fact that Coulson eventually became the glue of the MCUs Phase One - popping up in Iron Man 1 and 2, and setting Thor up, it became only natural that his character be the final step in cementing the team.
Its just a shame that it had to be done with his death - although it makes the most sense. Running afoul of Loki, by trying to stop him no less, was a heroic end for stoic agent. Its a shame he fell for the ol disappearing illusion trick, but what can you do. Thor falls for it all the time.
The kicker is his final line, dripping with Whedonitis - This was never going to work if we didnt give them something to. You can picture it now, Whedons self-satisfied smile, stroking a cat probably. But goddamn if it doesnt work a treat.