The unstoppable juggernaut that is the Marvel Cinematic Universe (not to be confused with the Juggernaut that Fox owns) is easily the most popular film franchise in the world. Each blockbuster epic has been seen by millions of people and are equally loved by fans who dig seeing their favourite characters on the big screen and newcomers who have never picked up a comic in their lives.
A big part of the MCU's success is down to the decades worth of great stories that the films have to pick from and the mixing and matching of various characters and storylines to condense hundreds of issues down into a single narrative.
A side-effect of this though is that a lot of characters and events go through changes during the transition from print to the big screen, either to bring them more in-line with modern standards or to help them better fit in with the overall narrative. Some of these changes have been pretty minor like ditching Thor's helmet or changing Heimdall's race (although some people would have you believe that's an almighty injustice, inevitably).
Sometimes though, these changes are so huge that a hero or villain can seem like a completely different character.
10. Hawkeye Has A Family
One of the surprise highlights of Age of Ultron was the revelation that Hawkeye has a wife and children. It was an unexpectedly touching moment that helped to flesh out the character beyond "good at arrows" and "likes purple".
It was also fairly ironic considering that, in the comics, one of Hawkeye's main defining features is that he is a notorious ladies man. Over the years, the skirt-chasing marksman has had numerous flings with heroes like Black Widow and Spider-Woman and, apart from being briefly married to Mockingbird, has spent most of his career single and very much ready to mingle.
This difference can probably be chalked up to the movie version of Hawkeye borrowing a lot of elements from the Ultimate version of Clint Barton. In that continuity, Clint was a member of the Ultimates (that universe's version of the Avengers) and worked for SHIELD as a Black Ops agent. Like the movie version, this Hawkeye was also married and had two children.
Ultimate Hawkeye's family ended up getting murdered by Black Widow when she betrayed the team so maybe let's hope that the movies don't take too much from the Ultimate Comics.