6) Black Widow
Fans have been asking for a solo adventure for Scarlett Johansson’s Black Widow ever since she first appeared in 2010’s Iron Man. Marvel chief Kevin Feige has frequently expressed interest in making the movie, although at other times he has stated that Natasha Romanoff works better as a supporting player.
Nonetheless, in May 2016, Feige confirmed that Marvel were now “committed” to making a solo film for the character, with the plan presumably being that it would fit somewhere in Phase Four. We can hope that it will actually come to pass this time, and not fall back down the to-do list at the studio.