Avengers: Infinity War - Predicting All 67 Characters
29. Black Panther
With many of the original Avengers' contracts running out, this two-parter is looking like a passing of the torch. One of the biggest "new" Avengers (although by this point Chadwick Boseman will have starred in two movies - Captain America: Civil War and Black Panther) is T'Challa, so, like Strange, expect Black Panther to play a substantial role in the narrative.
28. Shuri
Assuming T'Challa's father follows his comic counterpart and dies in Black Panther, the Wakandan supporting character most likely to appear in Infinity War is his sister, Shuri. A powerful fighter who eventually takes up the mantle herself, she'd not only brings some more diversity to the fight, but this would also set her up as a hero in her own right.
27. Captain Marvel
The other big new character in Phase 3 is Captain Marvel. With her own standalone coming in the middle of the two-parter, very little is known about the plans for Carol Danvers, although the gradual stream of rumours suggest we'll start hearing concrete things soon. With Marvel trying to step away from origin stories to a degree, she'll probably turn up in her movie fully formed, and thus is able to play a part in both Infinity War movies.
26. Adam Warlock
One character with a strong link to the Infinity Gems in the comics, and who has already been seeded in the movies, is Adam Warlock - his cocoon was in The Collector's museum, finally seen hatched at the end of Guardians Of The Galaxy. With such a strong comic heritage, it seems likely he'll make his presence overtly felt here; he is one of the biggest cosmic characters not brought to the big screen, after all.