So with the major additions being the Maximoffs and Ultron, we have more more more than enough issues to countdown with 637 days remaining. I'll start with the Maximoffs, go into their individual history, then move onto issues and stories featuring Ultron.
Okay, let's do this. B.A.U. = Before Age of Ultron
And we start with Scarlet Witch and Quicksilver fist joining the Avengers! I would have covered their first appearance in general but it seemed wrong to start off an Avengers countdown with an X-Men issue. Will start from the beginning from tomorrow onward.
2014 - Captain America: The Winter Soldier | The Amazing Spider-Man 2 | X-Men: Days of Future Past | Guardians of the Galaxy
2015 - The Avengers: Age of Ultron | The Fantastic Four | Ant-Man
2016 - Batman vs. Superman | X-Men: Apocalypse | The Amazing Spider-Man 3
TV - Arrow | The Flash | Gotham | Constantine | The Avenger | Hourman | iZOMBIE
TV - Agents of S.H.I.E.L.D. | Agent Carter | Daredevil | Luke Cage | Iron Fist | Jessica Jones | The Defenders