With Captain America stand AntMan, Sharon Carter, Falcon, and the Winter Soldier. With Iron Man are Black Widow, Black Panther, War Machine, and the Vision.
There are other characters expected to appear in the film, including Spider-Man, via Marvel’s new deal with Sony, for one (see “Sony Finds Its New Spider-Man”) and a variety of other announced cast members (see “Geek Movie News Round-Up”).
See gallery below for the newly released concept art.