Let me up front in saying, this list is incomplete, and will likely always remain so. Marvel may not have locked down their Phase 1 scripts much, but by Phase 2, scripts were impossible to get hold of. The only reason there are more for Phase 3 is that by that point Marvel had sufficient faith in their writers to start submitting them for Academy awards.
But I wanted a complete list of all the movies, so I could plug the gaps when scripts appeared in the wild.
Film U.S. release date Director Screenwriter(s) Iron Man May 2, 2008 Jon Favreau Mark Fergus & Hawk Ostby and Art Marcum & Matt Holloway The Incredible Hulk June 13, 2008 Louis Leterrier Zak Penn Iron Man 2 May 7, 2010 Jon Favreau Justin Theroux Thor May 6, 2011 Kenneth Branagh Ashley Edward Miller & Zack Stentz and Don Payne Captain America: The First Avenger July 22, 2011 Joe Johnston Christopher Markus & Stephen McFeely Marvel’s The Avengers May 4, 2012 Joss Whedon Joss Whedon Phase 2
Film U.S. release date Director(s) Screenwriter(s) Iron Man 3 May 3, 2013 Shane Black Drew Pearce and Shane Black Thor: The Dark World November 8, 2013 Alan Taylor Christopher L. Yost and Christopher Markus & Stephen McFeely Captain America: The Winter Soldier April 4, 2014 Anthony and Joe Russo Christopher Markus & Stephen McFeely Guardians of the Galaxy August 1, 2014 James Gunn James Gunn and Nicole Perlman Avengers: Age of Ultron May 1, 2015 Joss Whedon Joss Whedon Ant-Man July 17, 2015 Peyton Reed Edgar Wright & Joe Cornish and Adam McKay & Paul Rudd Phase 3
Film U.S. release date Director(s) Screenwriter(s) Captain America: Civil War May 6, 2016 Anthony and Joe Russo Christopher Markus & Stephen McFeely Doctor Strange November 4, 2016 Scott Derrickson Jon Spaihts and Scott Derrickson & C. Robert Cargill Guardians of the Galaxy Vol. 2 May 5, 2017 James Gunn James Gunn Spider-Man: Homecoming July 7, 2017 Jon Watts Jonathan Goldstein & John Francis Daley and Jon Watts & Christopher Ford and Chris McKenna & Erik Sommers Thor: Ragnarok November 3, 2017 Taika Waititi Eric Pearson and Craig Kyle & Christopher L. Yost Black Panther February 16, 2018 Ryan Coogler Ryan Coogler & Joe Robert Cole Avengers: Infinity War April 27, 2018 Anthony and Joe Russo Christopher Markus & Stephen McFeely Ant-Man and the Wasp July 6, 2018 Peyton Reed Chris McKenna & Erik Sommers and Paul Rudd, Andrew Barrer & Gabriel Ferrari Captain Marvel March 8, 2019 Anna Boden and Ryan Fleck Anna Boden & Ryan Fleck & Geneva Robertson-Dworet Avengers: Endgame April 26, 2019 Anthony and Joe Russo Christopher Markus & Stephen McFeely