Recently, Avengers: Age of Ultron writer/director Joss Whedon called Edgar Wright's Ant-Man script the best Marvel script he's ever read. Too bad that's not the version fans will see in theaters on July 17, 2015.
Originally, Wright and Joe Cornish wrote the MCU introduction for Henry Pym (Michael Douglass) and Scott Lang (Paul Rudd) before the Wright and Marvel Studios parted ways over creative differences. Wright and Cornish first started working on Ant-Man in 2003.
Adam McKay was brought in by Marvel to replace Wright as writer AND director but was unable to commit to directing due to scheduling conflicts. Marvel then came up with the solution of using McKay's script with Peyton Reed sitting in the director's chair. Throughout the revision process, lead actor Paul Rudd was also brought in to address script changes.
So here's how official writing credits shake down:
Ant-Man story by Edgar Wright & Joe Cornish
Ant-Man screenplay by Wright & Cornish and Adam McKay & Paul Rudd